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Ce  document  est  tWmi  au  taux  de  reduction  indique  ci-decsoui. 


lOx 

14x 

18x 

22x 

26x 

30x 

y 

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12x 


16x 


20x 


24x 


28x 


32x 


lb 


Th«  copy  fUmtd  h«r«  hat  b««n  raproducad  thanks 
to  tha  ganarosity  of: 

Stauffer  Library 
Queen's  University 

Tha  imagas  appaarJng  hara  ara  tha  »>•«  quality 
possibia  eonaidaring  tha  condition  and  laglblllty 
of  tha  original  copy  and  In  kaaping  with  tha 
filming  contract  apaciflcationa. 

Original  eopiaa  In  printad  papar  covara  ara  fllmad 
baginning  with  tha  front  cowar  and  anding  on 
tha  last  paga  with  a  printad  or  illuatratad  impraa- 
sion.  or  tha  back  covar  whan  appropriata.  All 
othor  original  eopiaa  ara  filn»ad  baginning  on  tha 
first  paga  with  a  printad  or  lllustratad  impraa- 
sion.  and  anding  on  tha  last  paga  ¥«Hth  a  printad 
or  illuatratad  impraasion. 


Tha  last  racordad  frama  on  aach  •"'"<»♦'«•;•  ^ 
shall  contain  tha  symbol  —^«maaning    CON- 
TINUED"), or  tha  symbol  V  (maanmg    END  I. 
whiehavar  spplias. 

Maps,  platas,  charts,  ate.  may  ba  fllmad  at 
diffarant  raduction  ratios.  Thosa  too  larga  to  ba 
antiraly  includad  in  ona  axposura  ara  fllmad 
baginning  In  tha  uppar  laft  hand  cornar.  laft  to 
right  and  top  to  bonom,  as  many  framas  as 
raquirad.  Tha  following  diagrams  iliustrata  tha 
mathod: 


L'axamplaira  film*  fut  raproduit  grica  i  la 
g^nirositi  da: 

Stauffer  Library 
Queen's  University 

Las  imagas  suivantas  ont  At*  raproduitas  avac  la 
plus  grand  soin,  compta  tanu  da  la  condition  at 
da  la  nattat*  da  l'axamplaira  film*,  at  ^n 
conf  ormit*  avac  las  conditions  du  contrat  da 
filmaga. 

Las  axamplairas  originaux  dont  la  couvartura  an 
papiar  ast  imprimia  sont  filmis  an  commancant 
par  la  pramiar  plat  at  an  tarminant  soit  par  la 
darni*ra  paga  qui  comporta  una  amprainta 
d'Imprassion  ou  d'illustration.  soit  par  la  sacond 
plat,  salon  la  cas.  Tous  las  autras  axamplairas 
originaux  sont  film*s  an  comman9ant  par  la 
prami*ra  paga  qui  comporta  una  amprainta 
d'Imprassion  ou  d'illustration  at  an  tarminant  par 
la  darni*ra  paga  qui  comporta  una  talla 
amprainta. 


Un  daa  symbolaa  suivants  apparaitra  sur  la 
darni*ra  imaga  da  ehaqua  microficha.  salon  la 
cas:  la  symbols  -^  signifia  '*  «"-»«•  - 
aymbola  ▼  signifia  "FIN  ". 


A  SUIVRE '.  la 


Las  cartas,  planchas.  tablaaux.  ate.  pauvant  *tra 
filmis  *  das  taux  da  reduction  diff«rants. 
Lorsqua  la  documant  ast  trop  grand  pour  *tra 
raproduit  an  un  saul  clich*.  il  ast  film*  *  partir 
da  I'angia  sup*riaur  gaucha.  da  gaucha  *  droita. 
at  da  haut  an  baa.  an  pranant  la  nombra 
d'imagas  n*cassaira.  Las  diagrammas  suivants 
illustrant  la  m*thoda. 


1  2  3 


MICROCOPY   RBOUITION   TBT  CHART 

(ANSI  and  ISO  TEST  CHART  No.  2) 


■  30 

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jj    -^IPPLIED  IfVMGE    In 


1653  East  Main   Street 

Rochester.    New   York         U609       U<U 

(716)    482  -  0300  -  Phone 

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7^ 


J 


A  MANUAL  OF  THE 

NORTH  AMERICAN 
GYMNOSPFRMS 


EXCLUSI\  E  OF  THE  CYCADALES  BUT 

TOGETHER  WITH  CERTAIN 

EXOTIC  SPECIES 


BV 

DAVID  PEARCE  PENHALLOVV,  D.Sc. 

MacDoNALU   PllOFES!i')K   OV   BoTANV,  McGlLI    UniVIKSITV 


BOSTON,  U.S.A. 

GINN  &  COMPANY,  ''UBLISHERS 

Q[it  3ttlieiucnm  {)te«8 

1907 


^^■<'%-i.(hT-. 


CorvmoHT,  10)07,  ■* 
DAVID  PKAKCK   PENHALLOW 


ALL    HICiHTS   IIKS«HV(U 


tt'S 


>>e  atttii««m  >c««« 

CINN  A  COMI'ANY  •  HRO- 
PRIETURS  •  BOSTON  .  U.S.A. 


(^     ^ 


^     r.. 


a 


TO  ONf 

WHO   HAS   ALWAYS    MANIFESTED 

THE   KEENEST   INTEREST   IN   MY   PROFESSIONAL   WORK, 

THIS   VOLUME   IS 

AFFECTIONATELY    DEDICATED,— 

MY   WIFE 


16311 


PREFACE 


In  presenting  this  volume  to  working  botanists  the  hope  is 
indulged  that  it  may  also  prove  of   service  to  engineers  and 
especially  to  foresters.    During  its  progress  through  the  press 
various  opportunities  have  been  offered  for  testing  not  only  the 
accuracy  and  value  of  the  diagnoses  for  the  recognition  of  woods 
about  the  identity  of  which  there  was  some  doubt,  but  also  its 
general  application  to  the  elucidation  of  important  questions 
relating  to  practical  forestry  ;  and  the  fact  that  such  a  work  is 
greatly  needed  at  this  time,  and  may  materially  assist  in  the 
development  of   modern  forestry,  has  been   strongly  empha- 
sized.    An  important  field  for  useful  research  may  be  found  in 
an  extension  of  the  studies  here  indicated,  not  only  with  respect 
to  exotic  gymnosperms,  but  in  their  application  to  dicotyledonous 
woods,  many  of  which  present  problems  of  great  scientific  interest 
and  practical  value. 

An  effort  has  been  made  to  keep  the  work  up  to  date,  espe- 
cially with  respect  to  the  treatment  of  fossil  woods,  but  the 
author  is  only  too  conscious  of  many  imperfections  which  it  is 
hoped  the  application  of  the  book  to  practical  service  may  assist 
in  making  clear  and  ultimately  removing. 


Montreal,  Canada 


D.  P.  PENHALLOW 


CONTENTS 


PART   I— ANATOMY 

Introduction  .... 

J 

CHAPTER 

I.  General  Directions  for  th     Preparation   of  Material  and  the  Value 

of  Particular  Sections i^^ 

II.  The  Growth  Ring:  its  structural  features  and  relation  to  age     ...     24 

III.  Tracheids:  spiral,  pitted,  and  resinous  wood  tracheids,— their  structure 

and  relation  to  development 

IV.  Bordered  Pits:  their  genesis,  structural  variations,  distribution,  and 

phylogenetic  relations 

V.  Medullary  Rays :  their  morphology  and  kinds .78 

VI.   Medullary  Rays  (.ontinueJ) :   ray  tracheids,- their  mon>hology  and 

distribution „„ 

VII.  Medullary  Rays  (f<,«//«;W):  relations  to  development  .     .     .     .  ,03 

VIII.  Wood  Parenchyma :  crystallogenous  idioblasts  and  resin  cells,  — their 

structure  and  relations  to  classification ,00 

IX.  Re.sin  Passages :  their  morphology I'^ 

X.  Resin  Passages  {co»/i„u,d) :  their  distribution  and  relations  to  phy- 

logeny,  and  classification <j 

XI.  General  Phylogeny  :  ba.sed  upon  the  data  of  the  preceding  chapters  '.  ,54 
XII.  Durability  of  Woods  and  their  Preservation  as  Fo.ssiIs  :  a  discussion 
of  the  principles  involved  in  the  durability  of  woods,  and  the  princi- 
pal ways  in  which  they  are  pre.served  in  a  fossil  state  .  ,6- 
XIII.  Decay:  Its  Mode  of  Action  and  Effects:  a  disc,  sion  of  the  chief 
factors  concerned  in  promoting  decay,  the  way  in  which  it  operates, 
and  the  principles  underlying  treatment  for  its  arrest 175 


PART   II  —  SYSTEMATIC 

Synopsis  of  Genera  for  the  Cordaitales,  Gingkoales,  and  Coniferales  ,nc 

Cordaitales -^^ 

Cordaites '\ 

Dammara     ...  '•'' 

,  .  201 

Araucana -^ 

Gingkoales       ...  °'^ 

Gingko     ...  '°'> 

20; 

vii 


viii  ANATOMY  OF  THE  GYMNOSPERMS 

PAbl 

Coniferales *'o 

Torreya 2'0 

Taxus ai2 

Thujopsis *IS 

Cryptomeria *|6 

Podocarpus 216 

Taxodium 217 

Libocedrus *I9 

Thuya 220 

Sequoia *23 

Cupressus 2*8 

Cupressoxylon 238 

Juniperus 244 

Abies 253 

Tsuga 265 

Pseudotsuga 271 

Larix 276 

Picea 281 

Pinus 291 

Section  I.    Soft  Pines 30S 

Section  II.    Hard  Pines 3'8 

Pityoxylon 34° 

Appendix  A:  Tables  of  Avvtomical  Data 3S3 

Appendix  B:  Volumes  of  Tracheids  and  Thickness  ok  Walls  .    .  358 

Literature 3^2 

Index 3^7 

Plates 375 


NORTH  AMERICAN  GYMNOSPERJViS 


Part  I — Anatomy 


Part  I— Anatomy 


INTRODUCTION 

The  present  work  had  its  origin  in  1880,  in  an  attcmr-t  to  con- 
strue   a  system  of  classification  for  the  North  American  Coniferje 
based  upon  the  anatomy  of  the  vascular  cylinder  of  the  t.iaturr 
stem.    The  fundamental  idea  was  that  such  i  classifica  ion  woula 
prove  of  great  value  in  the  identification  of  material  used  tor 
structural  purposes,  but  investigations  had  not  been  carried  very 
far  when  it  became  manifest  that  some  such  arrangement  was 
imperatively  demanded  in  other  directions  and  for  purposes  of 
a  more  strictly  scientific  character.    In  entering  upon  the  study 
of  fossil  plants  it  was  recognized  that  the  most  fruitful  source  of 
reliable  data  must  be  found  in  the  stem  structure.    At  that  time 
there  was  little  in  the  way  of  an  adequate  basis  for  further  study 
of  this  sort,  inasmuch  as  the  current  diagnoses  of  the  vascular 
structure  were  found  in  most  cases  to  be  singularly  inadequate, 
and  often  so  incorrect  as  to  require  extensive  revisions.    It  was 
found  furthermore  that  in  order  to  reach  correct  conclusions  in 
the  case  of  stems  which  must  often  present  marked  structural 
alterations,  arising  through  the  influence  of  decay  and  other  con- 
ditions attending  fossiJ..'ntion  in  its  various  fi)rms.  it  was  indis- 
pensable that  there  should  be  a  trustworthy  means  of  comparison 
with  existing  types,  whereby  sources  of  error  arising  from  elimi- 
nated structures  might  be  definitely  excluded,  and  the  ^ossil 
referred  with  certainty  to  its  nearest  relative.    The  original 
intention  was  therefore  modified  with  a  view  to  meeting  the 
requirements  of  paleobotanical  research.    During  the  time  these 
mvestigations  have  been  in  progress  there  has  been  much  change 
m  the  views  held  by  botanists  respecting  the  significance  of  ana- 
tomical features  as  affording  evidence  of  descent;  and  our  own 


4  ANATOMY  OF  THE  GYMNOSPERMS 

studies  brought  forth  facts  which  gave  repeated  emphasis  of  the 
most  positive  kind  to  the  idea  that  questions  of  phylogeny  cannot 
be  settled  either  by  the  morphologist  in  the  narrower  sense  or 
by  the  physiologist  when  acting  independently,  and  that  a  proper 
historical  point  of  view  can  be  gained  only  when  to  such  labors 
we  join  the  data  derival  from  a  critical  study  of  the  stem  structure 
in  all  its  details. 

The  original  intention  was  to  make  a  complete  study  of  all  the 
North  American  woods,  comprising,  as  enumerated  by  Sargent 
in  his  report  in  the  Tenth  Census  of  the  United  States,  some  four 
hundred  and  nineteen  species  and  varieties ;  but  the  great  impor- 
tance of  the  Coniferae  from  an  economic  point  of  view,  their  fre- 
quent representation  in  the  fossil  state,  and  their  relatively  more 
simple  structure  eventually  led  to  their  selection  as  the  one  group 
in  which  initial  studies  might  be  prosecuted  with  the  most  imme- 
diate and  profitable  results.  While  the  North  A  i..  lean  species 
constituted  the  original  basis,  various  exotic  species  were  added 
from  time  to  time,  with  the  result  that  our  studies,  as  now  com- 
pleted, comprise  ninety-two  species  from  North  America,  twenty- 
one  species  from  Japan,  and  four  species  from  Australasia.  This 
extension  has  proved  of  great  value,  not  only  from  a  paleonto- 
logical  ix)int  of  view  but  also  because  of  the  important  bearing 
such  exotic  types  have  had  in  the  solution  of  questions  relating 
to  descent. 

In  determining  the  particular  nature  of  the  material  to  be  dealt 
with  in  the  prosecution  of  these  studies  several  considerations 
of  fundamental  importance  were  kept  in  mind,  among  the  more 
prominent  of  which  we  may  consider  the  following. 

The  economic  application  of  wood  involves  the  employment, 
solely,  of  the  material  which  lies  within  the  woody  zone  between 
the  bark  and  the  pith.  It  was  therefore  held  that  for  the  recogni- 
tion of  timber  or  wood  derived  from  constructions  of  any  kind  that 
these  two  latter  regions  of  the  stem  would  be  worthless,  and  that 
a  system  should  be  devised  which  would,  if  possible,  permit  the 
recognition  of  the  species  apart  from  such  structures.  Experience 
has  not  only  shown  that  this  is  possible,  but  that  the  characters 


INTRODUCTION 


embodied  in  the  structure  of  the  pith  and  barl<  arc,  in  most  cases, 
least  definite,  and  therefore  of  minimum  '.akje  for  tliffcrential 
purposes.    Furthermore  the  structural  variitions  which  may  Ix; 
ussumed  to  arise  in  conformity  with  the  getiend  evolution  of  the 
species  or  genus  are  always  most  pronouncetl  in  the  xylem  struc- 
ture, in  consequence  of  which  the  latter  acquires  exceptional  value 
for  purposes  of  relationship  and  phylogeny.    Woody  plants  which 
are  found  in  the  fossil  state  often  show  a  complete  absence  of 
pith  structure,  due  to  the  operation  of  extended  decay  which  may 
have  been  initiated  before  the  tree  or  shrub  ceased  to  live.    Much 
more  commonly  fossil  plants  are  devoid  of  bark.    Instances  are 
on  record,  as  in  the  case  of  Juniperus  virginiana  from  the  Pleisto 
cene  clays,  in  which  the  plant  is  so  perfectly  and  hermetically 
sealed  up  as  to  permit  of  a  perfect  preservation  of  the  kirk  as 
well  as  of  other  portions  of  the  stem,  but  such  examples  are  com- 
paratively rare.    More  commonly  the  extended  maceration  and 
lecay  to  which  plants  are  subjected  before  silicification  or  calci- 
fication occurs,  involves  a  loosening  and  subsequent  removal  of 
the  bark,  especially  when  the  tree  is  subjected  to  such  mechanical 
action  as  is  associated  with  its  transport  by  water.    It  is  therefore 
obvious  that  any  system  of  classification  which  would  serve  the 
highest  purposes  for  paleontological   research   must  be  wholly 
independent  of  both  bark  and  the  pith.    Another  consideration 
oi  importance  in  this  connection  relates  to  regional  differences 
of  such  a  nature  that  different  parts  of  the  stem  exhibit  more 
or  less  striking  variations  of  structural  detail.    As  these  will  be 
dealt  with  somewhat  in  detail  in  a  subsequent  chapter,  it  will  be 
sufficient  for  the  present  purpose  to  indicate  that  the  characters 
upon  which  the  generic  and  specific  differentiations  rest  are 
essentially  independent  of  location,  and  it  therefore  matters  not 
whether  the  sample  selected  comes  from  a  branch  or  the  main 
stem,  or  whether  it  is  derived  from  the  top,  bottom,  center,  or 
circumference  of  the  latter,  though  as  a  matter  of  preference  the 
wood  of  a  mature  stem  would  be  selected  as  furnishing  the  best 
average  conditions  of  structtirc,  and  therefore  the  greatest  facility 
in  determination. 


6  ANATOMY  OF  THE  GYMNOSPERMS 

Two  objects  have  been  helc'  in  view  in  the  preparation  of  this 
work :  (i)  its  application  to  the  needs  of  the  scientific  botanist 
in  prosecuting  researches  cither  in  recent  or  fossil  forms,  and 
(2)  its  adaptation  to  the  requirements  of  the  practical  engineer 
who  may  be  called  upon  to  recognize  material  entering  into  the 
construction  of  bridges  or  other  important  works.  While,  there- 
fore, Part  I  deals  primarily  with  the  anatomy  of  the  stem,  dis- 
cussing such  features  as  are  essential  to  a  correct  knowledge 
and  interpretation  of  the  systematic  portion,  it  also  includes 
special  chapters  having  a  more  or  less  direct  bearing  upon  the 
practical  utility  of  w  ods,  —  such  as  may  be  found  in  those  on  the 
general  mode  of  operation  of  fungus  parasites,  the  durability  of 
woods  under  different  conditions,  and  the  specific  action  of  decay 
upon  the  tissues.  Owing  to  the  great  extent  of  ground  covered 
by  the  subject  of  timber  diseases  and  the  special  methods  to  be 
employed  for  their  control,  and  the  fact  that  an  adequate  discus- 
sion of  these  important  topics  would  extend  the  present  work 
much  beyond  all  reasonable  limits,  the  reader  is  referred  for  the 
treatment  of  diseases  to  Tubeuf  (72),  and  for  methods  of  wood 
preservation  to  important  papers  by  Flad  (20)  and  Constable 
(10).  If  such  treatment  of  the  general  subject  serves  to  secure 
a  wider  constituency  among  those  who  are  called  upon  to  make 
large  use  of  valuable  woods,  one  of  the  larger  aims  of  the 
present  work  will  have  been  achieved. 

Part  IT  (3  based  upon  the  details  of  Part  I,  and  it  relates 
exclusively  to  questions  of  classification  and  relationship.  In 
attempting  to  construct  a  classification  of  the  Coniferales  upon 
the  basis  of  the  anatomical  characters  to  be  found  in  the  woody 
portion  of  the  stem,  it  appeared  that  there  was  little  to  be  obtained 
from  the  work  of  previous  investigators  which  could  be  employed 
as  a  satisfactory  woiking  basis,  since  the  results  recorded  by 
Nordlinger,  Hartig,  Muller,  and  others,  while  of  great  impor- 
tance with  respect  to  certain  aspects  of  structure  and  afford- 
ing many  important  suggestions,  had  not  been  carried  to  that 
point  where  they  could  be  reduced  to  any  very  great  practical 
utility.  A  survey  of  the  literature  of  the  subject  showed  that 


INTRODUCTION  y 

the  study  of  a  particiOar  group  of  woods  was  not  sufficiently 
exhaustive  to  permit  of  final  inclusions,  and  that    in   many 
cases  the  dugno.scs  were  not  drawn  with  sufficient  attention 
to  strict  accuracy  of  statement  and  that  regard  for  exhaustive 
deta.1  which  would  render  them  of  the  greatest  value.    In  deal- 
ing  with  the  structure  of  the  wood  for  taxonomic  purposes  it 
has  been  found  that  the  diagnosis  must  take  cognizance  of  a 
wide  range  of  detail,  and  that  it  must  be  most  searching  in 
Its  character.    This  is  a  necessary  result  of  the  high  degree  of 
development  of  the  organisms  and  the  consequent  differentia- 
tion of  the  structure  along  several  lines  of  development     It  is  a 
neglect  of  this  fact  in  the  past  which  appears  to  explain  why 
previous  investigators  have  failed  to  construct  a  system  of  cla,si. 
fication  which  would  not  only  give  some  additional  information 
respecting  phylogeny,  but  which  would  at  the  same  time  permit 
of  a  satisfactory  recognition  of  species  and  genera.  Under  these 
circumstances  it  appeared  desirable  to  commence  ./.-  novo  and 
in  the  first  instance,  make  an  exhaustive  study  of  the  anatomy 
of  the  wood,  utilizing  for  purposes  of  classification  such  facts 
as  might  be  obtained  in  this  way.    As  a  convenient  starting 
point  tor  the  discussion  of  relationships  it  was  considered  that 
none  could  be  secured  which  would  be  better  adapted  to  the 
purpose  m  view  than  the  classification  generally  employed  as 
based  upon  the  external  morphology  of  the  vegetative  organs 
and  inflorescence.    For  this  purpose  I  at  first  selected  the  then 
most  recent  and  authoritative  compilation  relating  to  the  North 
American  Coniferales.  as  embodied  in  Professor  Sargent's  valu- 
able  work  on  the  woods  of  North  America  in  the  Tenth  Census 
of  the  United  States.    To  this  were  later  added  Sargent  s  Silva 
0/ North  America  and    ne  sequence  of  Engler  and  Prantl  con- 
ained  m  the  Natur/ic/uu  Pflanzcnfantilicn,  as  expressing  the 
latest  views  c.i  the  subject. 

Assuming  the  typical  character  of  the  trees  discussed  by 
Sargent,  it  was  held  that  any  well-authenticated  specimen  of 
wood  rom  any  such  tree  would  also  be  typical,  and  in  this  way 
It  would  be  possible  to  form  a  type  series  the  structure  of  which 


ANATOMY  OF  TIIK  f;N  MNOSI'KHMS 


could  bo  discussetl  with  direct  reference  to  the  aKAiimcd  rclati  >n- 
ships  based  uium  external  i  haractcrs.  The  nucleus  of  such  a 
type  scries  was  found  in  the  Sr.rgcnt  collection  of  woods  derived 
from  his  work  in  connection  with  the  Tenth  Census.  To  this 
other  specimens  were  added  through  the  ccjrtesy  of  Professor 
Sargent  and  Mr.  J.  G.  Jack  of  the  Arnold  Arboretum ;  Dr. 
N.  L.  Britton  of  Columbia  University,  and  now  Director  of  fht 
New  York  Botanical  Garden  ;  Mr.  Morr's  K.  Jesup,  President 
of  the  American  Museum  of  Natural  History;  and  Dr.  B.  E. 
Fernow,  then  Chief  Forester  of  the  United  States  Department  of 
Agriculture,  also  to  the  late  Baron  P'erdinand  von  Mueller  of 
Melbourne,  Australia ;  Sir  VV.  T.  Thiselton-Dyer,  late  Director 
of  the  Royal  Gardens,  Kew;  Mr.  K.  J.  Maxwell  of  Montreal;  and 
more  recently  Dr.  E.  C.  Jeffrey  of  Harvard  University ;  to  all  of 
whom  my  grateful  acknowledgments  are  due.  Yet  other  speci- 
mens were  obtained  by  personal  collection  or  from  trustworthy 
collectors  whose  reputation  was  sufficient  guarantee  for  their 
authenticity.  In  this  way  it  has  been  possible  to  include  in  the 
present  list  all  of  the  North  American  species  of  the  Coniferales 
as  enumerated  by  Sargent  in  his  Stha,  with  the  exception  of  the 
recently  described  Juniperus  flaccida.  Present  lack  of  material 
has  also  prevented  me  from  making  a  critical  study  of  Junijierus 
barbadcnsis  in  order  to  determine  anatomically  the  identity 
wliich  Sargent  establishes  on  the  basis  of  external  characters ; 
while  t  e  same  comlitions  have  also  barred  a  study  of  Juniperus 
scopulorum,  Sargent,  and  Cupressus  pygmaca,  Sargent,  with  a 
view  to  determining  their  validity  as  distinct  species. 

During  the  progress  of  the  present  studies  a  large  amount  of 
material  came  to  hand  from  Japan  and  Australia.  Its  elabora- 
tion has  afforded  much  information  of  the  highest  value,  and  it 
has  been  considered  expedient  to  incorporate  it  in  the  present 
classification. 

With  this  material  in  hand  the  first  step  was  to  secure  an 
accurate  diagnosis  of  each  species  for  each  of  the  three  sections 
usual  in  such  cases,  and  when  it  is  recalled  that,  as  at  present 
elaborated,  this  involved  a  critical  study  of  twenty  genera  and 


one  hiiiulrcd  ami  sixteen  !*|)ccic»,  thus  representing  a  total  <»f 
three  hundred  and  fortyeight  sections,  and  that  the  diagn(.scs 
wc'"  at  first  of  a  purely  tentative  character  demanding  frequent 
revision  and  extensi(.n,  it  will  he  understood  that  the  enormous 
mass  of  detail  involveil  not  only  presented  considerable  diffi- 
culties but  demanded  the  expenditure  of  much  time  and  most 
patient  and  painstaking  effort.    The  concurrent  prosecution  of 
IKiIeontological  studies,  in  which  a  very  critical  means  of  differ- 
entiation  was  called  for,  because  of  structural  djfccts  arising 
from  decay  and  other  influences  attendant  upon  the  process,  of 
fossilization,  fortunately  gave  jusi  the  insight  into  the  require- 
ments of  critical  diagnoses  whic.i  was  required.    It  soon  became 
clear  that  certain  anatomical  fer.tures  stood  forth  with  very  great 
prominence,  and  that  they  could  be  successfully  employed  for 
the  recognition  of  primary  and  secondary  divisions  of  the  group  ; 
while   other   less  prominent  characters  naturally  fell  into  the 
categories  of  those  which  define  genera  and  species.    Upon  this 
basis  it  was  :>oon  possible  to  difTerentiatc  the  various  genera  with 
acc    dcy,  as  already  set  forth  in  previous  publications  (44).   The 
systematic  treatment  cf  the  genera  of  the  North  American  Coni- 
ferales  then  elaborated  has  been  in  constant  and  successful  use 
for  several  years,  as  applied  to  the  determination  of  both  fossil 
and  recent  woods.    Such  experience  has  shown  the  classification 
to  b  ;  iubstantially  correct  with  respect  to  the  accuracy  of  the 
diagnoses  and  the  efficiency  of  the  artificial  key  connected  there- 
with.   A  few  minor  changes  have  been  found  necessary,  anu 
these  have  been  introduced  in  connection  with  the  more  recent 
revisions.    Later  experience,  especially  as  derived  from  a  more 
critical  study  of  the  anatomical  details,  has  shown  the  need  of  a 
revision  of  the  generic  and  specific  sequences,  us  embodied  in 
recently  published  papers  (59)  and  now  incorporated  here.    As 
it  now  stands,  comparatively  slight  familiarity  'vilh  the  classifi- 
cation will  enable  one  to  refer  most  woods  to  their  appropriate 
genera  without  hesitation.    Thus  Taxus,  Torreya,  and  Pseudo- 
tsuga  may  be  isolated  at  once  by  the  single  character  which  they 
possess  in  common,  —  tracheids  with  spirals,  —  while  the  last 


lO 


ANATOMY  OF  THE  GYMNOSPERMS 


genus  may  be  differentiated  from  the  other  two  by  the  very 
simple,  constant,  and  well-defined  characteristics  found  in  the 
presence  of  resin  jiassagos  and  fusiform  rays.  Yet  once  more, 
Pseudotsuga,  Larix,  Picca,  and  Pinus  fall  into  a  natural  group 
characterized  by  the  i)resence  of  resin  passages,  and  within  the 
group  differentiation  of  the  individual  genera  follows  on  natural 
and  simple  lines.  This  is  particularly  true  of  Pseudotsuga  and 
Pinus,  in  each  of  which  the  generic  characters  are  so  well  defined 
as  to  leave  no  room  for  doubt ;  while  yet  once  more,  Pinus  may 
be  subdivided  into  well-defined  groups,  or  subgenera,  representa- 
tive of  the  soft  and  hard  pines.  Abies  and  Tsuga  are  differen- 
tiated by  the  position  of  the  resin  cells  and  the  character  of  the 
terminal  walls  of  the  ray  cells ;  Sequoia  and  Taxodium  are  sep- 
arated by  the  terminal  walls  of  the  ray  cells,  the  character  of 
the  bordered  pits  on  the  lateral  walls  of  the  ray  cells,  and  by  the 
distribution  of  the  resin  cells  ;  Cupressus  and  Thuya  are  differ- 
entiated by  the  terminal  walls  of  the  ray  cells,  the  distribution 
of  the  resin  cells,  the  form  of  the  pits  on  the  lateral  walls  of  the 
ray  cells,  and  the  form  of  the  ray  cells  in  tangential  section. 
These  principles  are  applicable  to  all  other  genera,  and  the  key 
as  now  presented  affords  a  trustworthy  guide. 

For  the  species  the  question  has  been  found  to  involve  much 
greater  difficulties,  especially  with  reference  to  the  genus  Pinus, 
in  which  the  number  of  essential  elements  increases  greatly, 
while  extreme  variation  also  introduces  a  factor  which  adds 
much  to  the  complexity  of  the  problem.  Two  sources  of  error 
were  early  recognized  as  probable,  —  (i)  incorrectly  drawn  or 
incomplete  diagnoses,  and  (2)  deviation  from  the  selected  type. 
The  problem  was  to  elaborate  an  analytical  key  of  such  com- 
pleteness as  l;<  eliminate  any  such  errors,  and  then  apply  to 
it  a  test  which  would  prove  the  extent  of  its  accuracy,  em- 
ploying the  data  so  obtained  in  further  corrections  if  necessary. 
For  the  purposes  of  a  critical  test  I  was  furnished  with  care- 
fully selected  material  by  Mr.  Jack  and  Dr.  Fernow  to  the  ex- 
tent of  eighty-five  specimens  representative  of  fourteen  genera 
and  forty-nine  species.    The  specimens  received  from  Mr.  Jack 


INTRODUCTION  , , 

represented  a  great  variety  of  material  in  common  use  for  struc- 
tural purposes.    They  included  wood  not  only  from  the  mature 
parts  of  the  stem  but  also  from  the  center  of  the  trunk,  em- 
bracing in  some  instances  the  structure  of  the  pith  and  primary 
wood  zone.    For  these  reasons   they  possessed  special  value, 
inasmuch  as   they  afforded  an  opportunity  to  determine  the 
extent  and  nature  of  those  structural  variations  which  I  had 
some  reason  to  believe  existed,  as  between  the  earlier  and  later 
growths  of  the  stem.    In  transmitting  his  material  Dr.  Fernow 
stated  that  he  had  selected  it  "  with  reference  to  representing 
typical  wood,  and  it  was  not  taken  from  butt  logs,  top  logs, 
nor  branches  or  knots."    It  therefore  represented  exactly  the 
problems  which  would  be  met  with  in  every-day  practice. 

The  results  of  these  tests  as  at  first  obtained  were  far  from 
satisfactory.    They  clearly  proved  that  the  genera  could  be  recog- 
nized with  ease,  but  for  the  species  they  made  it  clear  that  there 
was  need  for  a  far  more  detailed  diagnosis  and  differential  key 
than  was  at  first  supposed  to  be  necessary.    More  searching 
studies  were  made  not  only  with  respect  to  existing  types  but  also 
as  applied  to  fossil  species  from  the  Devonian  to  the  Interglacial. 
These  studies  necessitated  frequent  recastings  of  diagnoses  and 
corresponding  alterations  of  the  analytical  key.    They  brought  to 
light  many  important  facts  and  relationships  of  the  greatest  value 
from  a  phylogenetic  point  of  view  as  well  as  from  the  taxonomic, 
and  they  served  to  emphasize  the  fact  that  many  of  the  more 
detailed  structural  features  of  the  pines  in  particular,  hitherto 
supposed  to  be  of  little  or  no  value,  were  in  reality  of  the  greatest 
importance.   A  final  application  of  the  test  specimens  under  the 
precise  conditions  which  would  obtain  in  ordinary  practice  showed 
a  verification  of  91.5  per  cent  for  all  genera  and  species.    In  this 
connection  it  may  be  of  interest  to  note  that  the  greatest  sources 
of  error  were  to  be  found  in  the  second  section  of  the  genus 
Pinus,  particularly  in  P.  taeda,  P.  echinata,  and  P.  glabra  in  the 
order  given,  whence  it  appears  that  these  species  stand  out  as 
the  most  variable  of  the  entire  Coniferales  and,  on  the  whole,  the 
most  difficult  to  determine.    This  is  in  precise  accord  with  the 


12 


ANATOMY  OF  THE  GYMNOSPERMS 


fact  that  these  species  are  among  the  most  highly  specialized 
representatives  of  the  entire  phylum,  and  that  they  therefore 
stand  as  representatives  of  the  highest  order  of  development. 
The  sources  of  error  having  been  determined  by  such  tests,  cor- 
rections were  applied  to  the  key  in  such  a  way  as  to  eliminate 
them,  while  the  original  diagnoses  were  further  modified  to  meet 
the  special  requirements.  It  is  manifestly  impossible  to  construct 
a  key  capable  of  providing  for  all  exceptional  cases.  These  can 
only  be  met  by  the  experience  of  the  observer  or  by  final  refer- 
ence to  and  critical  comparison  with  type  specimens.  But  the 
experience  so  far  gained  justifies  the  belief  that  as  now  presented 
the  key  affords  sufficient  data  for  the  recognition  of  species  under 
all  ordinary  circumstances,  and  then"  is  no  reason  for  hesitation 
in  stating  that  it  is  fully  as  efficient  in  this  respect  as  the  keys 
usually  employed  for  the  determination  of  species  on  the  basis 
of  external  morphology. 

In  the  employment  of  this  classification  the  novice  will  en- 
counter certain  practical  difficulties  the  nature  of  some  of  which 
it  may  be  well  to  indicate.  In  the  genus  Picea  the  differentiation 
of  species  is  attended  with  more  than  the  usual  difficulty,  and 
the  same  fact  appears  once  more  in  the  second  division  of  the 
genus  Pinus.  This  appears  to  be  the  result  of  a  general  advance 
toward  a  higher  type  of  development,  in  consequence  of  which 
there  is  a  more  uniform  distribution  of  similar  characters  among 
the  various  species.  This  feature  also  appears  occasionally  in 
other  genera,  especially  in  Juniperus,  where  it  is  not  altogether 
easy  to  differentiate  J.  nana  from  J.  communis,  of  which  it  has 
commonly  been  regarded  as  a  varietal  form.  But  J.  rigida  shows 
precisely  the  same  relations  to  both  of  these,  and  I  therefore 
prefer  to  retain  the  specific  status  of  all  three,  though  somewhat 
provisionally.  In  Pseudotsuga  there  is  as  much  anatomical  differ- 
ence between  P.  Douglasii  and  P.  macrocarpa  as  there  is  between 
any  well-Lnown  and  well-recognized  species.  There  is  therefore 
no  reason  for  assigning  the  latter  to  a  varietal  position,  and  it 
should  be  given  the  status  of  a  species,  as  correctly  suggested 
by  Sargent.  In  the  genus  Pinus,  P.  Murrayana  cannot  be  regarded 


INTRODUCTION 


»3 


as  anatomically  identical  with  P.  contorta,  as  suggested  by  Sar- 
gent, for  the  same  reasons  as  already  applied  to  Pseudotsuga. 
Similarly  P.  Jeffreyi  is  a  valid  species  and  P.  ponderosa  scopu- 
lorum  must  be  raised  to  the  position  of  a  species,  while  yet  others 
fall  into  the  same  category. 

The  sequence  of  genera  and  species,  as  well  as  the  relations 
of  the  larger  groups,  is  based  upon  the  anatomical  data  presented 
in  Part  I,  and  it  will  be  found  to  deviate  considerably  from  most 
of  the  systems  of  classification  now  in  use.  In  exhibiting  this 
sequence,  which  appears  abundantly  justified  from  one  point 
of  view,  it  must  nevertheless  be  carefully  k.  jit  in  mind  that 
su^h  an  arrangement  is  in  no  sense  regarded  as  fin;?'.  At  best 
it  is  a  purely  tentative  measure,  which  shall  ser\e  as  a  contri- 
bution toward  f  final  classification,  and  this  latter  can  be  com- 
pleted only  when  data  from  several  sources  are  assembled  and 
coordinated. 

As  derived  from  our  present  studies  the  sequence  of  the 
Gymnosperms  may  be  stated  as  in  table  on  the  following  page. 
With  respect  to  fossil  forms  an  effort  has  been  made  to  include 
all  known  North  American  species  so  far  as  they  have  been 
recognized  through  the  structure  of  the  wood  alone.    These  have 
been  included  under  their  respective  genera  as  now  known  for 
existing  .species,  and  thus  Cupressinoxylon »  or  Cupressoxylon  are 
described  under  Cupressus,  while  Pinoxylon  and  Pityoxylon  fall 
under  Pinus.    Unfortunately,  in  most  cases,  it  is  not  possible  t.. 
determine  the  structural  characters  with  that  detailed  thorough- 
ness which  is  desirable,  owing  to  the  imperfect  nature  of  the 
material,  and  it  has  therefore  been  found  necessary  to  arrange 
the  fossil  species  in  a  separate  section  of  the  genus  and  provide 
separate  analytical  keys.    The  very  great  difficulty  of  obtaining 
full  differential  characters  necessitates  reference  to  type  speci- 
mens whenever  a  serious  doubt  arises.    In  several  cases  the 

>  The  genus  Cupressinoxylon,  as  elsewhere  shown,  embraces  what  may  prove 
upon  revision  of  existing  descriptions  Sequoia  in  some  cases  and  Cupressus 
m  other  cases,  while  according  to  Jeffrey's  latest  publications  he  employs  the 
term  for  fossil  Sequoias.  Provisionally  I  prefer  to  include  it  under  the 'genus 
Cupressus. 


14 


ANATOMY  OF  THE  GYMNOSl'ERMS 


Class      I.   Cycadales. 

II.     CORDAITALES. 

Order  i.    Cordaitae. 

Family  i.    Cordaitacea. 

Genus  i.    Cordaites. 

2.  Araucariinea:. 

2.  Araucariae. 

1.  Dammara. 

2.  Araucaria. 

III.     GiNGKOALES. 

3.  Gingkoinex. 

3.  Gingkoaceac. 

1.  Gingko. 

IV.     CONIFERALES. 

4.  Taxoidex. 

4.  Taxacea;. 

1.  Torreya. 

2.  Taxus. 

5.  Podocarpacea. 

I.  Podocarpus. 

5.  Coniferae. 

6.  Taxodiineze. 

1.  Cr}'ptomeria. 

2.  Taxodium. 

3.  Sequoia. 

7.  Cupressineae. 

1.  Thujopsis. 

2.  Libocedrus. 

3.  Thuya. 

4.  Cupressus. 

5.  Juniperus. 

8.  Abietinex. 

1.  Abie.s. 

2.  Tsuga. 

3.  Pseudotsuga. 

4.  Larix. 

5.  Picea. 

9.  Pinoidex. 

I.  Pinus. 


INTRODUCIION 


'5 


diagnoses  are  given  provisionally,  since  it  is  quite  probable  that 
in  consequence  of  the  fragmentary  nature  of  the  available  mate- 
rial future  studies  will  show  several  supposed  species  to  be  really 
identical  with  one  another.  In  the  case  of  a  large  number  of 
fossil  species  it  has  not  been  found  possible  to  obtain  the  type 
sections  for  descriptive  purposes.  Under  these  circumstances, 
although  the  original  diagnoses  differ  materially  from  the  general 
plan  adopted,  it  has  been  thought  best  to  incorporate  them  in 
the  form  of  first  publication,  but  with  the  name  of  the  author 
appended. 

All  of  the  illustrations  emi-loyed  in  the  preparation  of  the 
present  work  have  been  prepared  from  drawings  and  photographs 
by  fhe  author,  and  they  may  therefore  be  regarded  as  being  par- 
ticularly applicable  to  the  various  questions  brought  under  dis- 
cussion. Nearly  all  the  text  figures  were  first  published  in  the 
American  Xatiiralist,  and  are  here  reproduced  through  the  cour- 
tesy of  that  journal.  Some  of  the  half-tone  reproductions  cf 
photomicrographs  appeared  in  earlier  papers  relating  to  fossil 
and  recent  gymnosperms,  while  yet  other'  are  introduced  here 
for  the  first  time.  It  has  been  impossible  to  introduce  ail  the 
illustrations  which  the  clearest  e.xposition  might  make  desirable, 
owing  to  the  limitations  imposed  by  the  expense  of  such  a  pro- 
ceeding ;  but  it  is  felt  that  the  very  generous  allowance  made  by 
the  publishers  in  this  respect  will  suffice  to  render  the  leading 
facts  of  structure  and  relationship  clear  enough  for  our  present 
purpose. 


rl 


CHAPTER   I 


GENERAL  DIRECTIONS  AS  TO  THE  PREPARATION 

OF  MATERIAL  AND  THE   VALUE  OF 

PARTICULAR  SECTIONS 

In  determining  the  course  to  be  followed  in  the  preparation  of 
material  and  its  subsequent  study,  it  is  impossible  to  too  strongly 
emphasize  the  fict  that  a  correct  and  complete  conception  of  the 
details  of  struct  ire  embraced  in  the  vascular  cylinder  of  the  3tem 
can  be  obtained  only  when  the  latter  is  studied  from  three  points 
of  view,  or  in  three  planes  of  section,  —  the  transverse,  the  radial, 
and  the  tangential,  the  last  two  of  which  are  of  necessity  also 
longitudinal.  Although  the  importance  of  these  three  planes  of 
section  is  well  recognized  by  scientific  botanists,  it  seems  desirable 
to  restate  the  fact  in  order  to  avoid  any  misconception  which 
might  otherwise  arise  through  the  minor  importance  attached  to 
the  longitudinal  sections  by  recent  authors  (79,  350).  Under  cer- 
tain circumstances  it  sometimes  happens  that  all  three  planes  of 
section  are  not  available,  and  the  student  is  then  compelled  to 
rely  upon  two  points  of  view  or  possibly  even  one  for  his  con- 
clusions. In  such  an  extremity  it  becomes  possible  to  draw 
deductions  from  the  material  in  hand  as  to  the  aspects  of  the 
structure  presented  by  the  remaining  plane  or  planes  of  section, 
and  so  to  reconstruct  with  approximate  accuracy  the  entire 
fabric.  But  such  a  method  should  never  be  resorted  to  except 
when  absolutely  necessary,  since  to  employ  it  under  other  cir- 
cumstances would  involve  a  measure  of  doubt  which  would  bring 
justifiable  discredit  upon  the  conclusions  reached.  The  relative 
value  of  each  section  for  such  purposes  will  appear  shortly. 

In  proceeding  to  the  study  of  a  given  wood  too  much  stress 
cannot  be  placed  upon  the  importance  of  very  searching  and  accu- 
rate observations,  especially  if  one  is  about  to  draw  a  diagnosis 

16 


GENERAL  DIRECTIONS  ,- 

of  a  new  species.    In  making  a  diagnosis  for  comparison  with 
that  of  a  previously  described  species  similar  care  is  a  neces- 
sity, particularly  in  the  case  of  the  different  hard  pines,  where  a 
comparatively  slight  deviation  may  involve  one  in  considerable 
difficulty.    Until  one  is  thoroughly  familiar  with  the  course  of 
procedure  to  be  followed,  and  has  an  extensive  knowledge  of  the 
anatomical  details  in  all  their  varying  aspects  as  characteristic 
of  different  genera  and  species,  the  only  safe  course  to  follow 
when  attempting  to  identify  a  species,  is  to  make  a  carefully 
written  diagnosis  in  full.    After  this  is  done  comparison  with 
the  key  or  with  the  supposed  species  may  be  made  in  detail     A 
comparatively  brief  acquaintance  with  the  systematic  portion  of 
this  work  will  enable  one  to  recognize  most  of  the  genera  at 
sight,  since  the  characters  arc  in  most  cases  very  clearly  defined 
and  easy  of  recognition  ;  but  the  same  does  not  hold  true  of 
species,  since  these  are  defined  by  a  larger  number  of  characters 
which  vary  somewhat  widely,  and  exceptional  cases  are  of  much 
greater  frequency.    Where  there  is  a  final  doubt  as  to  the  iden- 
tity of  a  given  species,  the  specimen  should  be  compared  with  a 
type  section  or  be  submitted  to  an  expert  for  decision. 

The  transverse  section  exhibits  in  the  main  an  end  view  of  the 
various  component  elements.    It  should  always  be  the  first  of 
the  three  to  be  examined,  since  it  immediately  permits  a  separa- 
tion of  the  genera  into  two  great  groups  and  affords  suggestions 
of  such  a  nature  as  to  permit  of  economy  of  time  at  a  later  stage 
of  the  examination.    It  conveys  a  correct  conception  of  the  pres- 
ence or  absence  of  certain  structural  features,  such   as  resin 
passages,  resin  cells,  or  resin  cysts  and  the  presence  or  absence 
of  thyloses;  it  affords  the  only  accurate  measure  of  regional  dis- 
tribution and  of  the  general  character  of  the  growth  rings  the 
relative  volume  and  character  of  the  spring  and  summer  woods, 
and  of  the  variations  which  distinguish  the  tracheids  of  those 
regions  of  growth.    When  elements  have  similar  terminal  aspects 
as  the  spiral  and  pitted  tracheids,  as  well  as  wood  parenchyma 
and  parenchyma  tracheids,  the  transverse  section  has  no  special 
value  beyond  that  which   is  to  be   found  in  a  recognition  of 


I8 


ANATOMY  OF  THE  GYMNOSFKRMS 


regional  distribution,  although  to  a  limited  extent  it  is  true  that 
certain  aspects  of  these  elements  may  lead  to  correct  inferences 
as  to  their  structural  features  when  displayed  in  other  planes  of 
section,  whereby  approximately  correct  data  may  be  obtained 
even  in  the  absence  of  longitudinal  sections.  This  is  particularly 
true  with  respect  to  the  distribution  of  the  resin  i^assajjes,  the 
relations  of  their  longitudinal  and  radial  distribution  being  such 
that  where  the  one  occurs  the  other  may  l)e  inferred ;  hence,  if 
resin  passages  occur  in  the  transverse  section,  we  may  conclude 
with  certainty  that  they  are  also  to  be  found  in  certain  of  the 
medullary  rays,  which  will  also  present  a  fusiform  aspect  in  tan- 
gential section.'  The  general  character  of  the  medullaiy  ray  is 
also  displayed  in  this  plane  of  section,  but  in  its  least  important 
aspect.  Although  all  the  details  of  width  and  composition  may 
be  obtained  much  more  accurately,  and  in  some  cases  only  from 
longitudinal  sections,  nevertheless  the  absence  of  these  latter 
enables  us  to  determine  from  the  transverse  section  whether  the 
rays  are  one  or  more  seriate  and  if  some  of  them  contain  resin 
passages. 

In  order  that  the  features  thus  indicated  may  be  exhibited  in 
their  typical  aspects,  it  is  of  the  greatest  importance  that  the 
plane  of  section  be  exactly  at  right  angles  to  the  axis  of  growth, 
otherwise  the  distortion  of  structure  which  necessarily  results 
will  not  only  make  observation  difficult,  but  it  will  serve  to 
seriously  impair  the  accuracy  and  value  of  any  diagnosis  which 
may  be  drawn. 

The  radial  section  is  also  a  longitudinal  section  the  plane  of 
which  should  exactly  coincide  with  the  radius  of  the  stem.  Any 
deviation  from  this  position  will  cause  the  section  to  become 
more  or  less  tangential,  and  just  in  proportion  as  it  approaches 
this  latter  will  its  value  diminish.  In  stems  or  branches  more 
than  five  centimeters  in  diameter  there  should  not  be  the  least 
difficulty  in  securing  the  desired  result,  inasmuch  as  the  abun- 
dance of  material  will  admit  of  somewhat  reckless  cutting ;  but 
in  small  branches  of  one  centimeter  or  less,  such  as  one  must 

'  Certain  exceptions  to  this  law  are  to  be  met  with  in  the  case  of  fossil  species. 


GENERAL  DIRECTIONS  ,g 

encounter  in  the  case  of  fossil  material,  great  care  should  be 
exercised  in  order  to  secure  the  few  truly  radial  sections  which 
the  scanty  material  affords.    When  properly  prepared  such  radial 
sections  supply  some  of  the  most  important  data  for  diagnostic 
purposes.    They  furni.sh  but  little  information  as  to  regional  dis- 
tribution, a  feature  which  is  of  secondary  importance  in  this  case 
They  do,  however,  furnish  evidence  of  the  highest  value  as  to 
the  form  and  structure  of  the  trachcids,  the  character  and  extent 
of  the  transition  zone,  the  regional  distribution  of  the  bordered 
pits  and  the  various  important  details  of  their  structure,  size,  and 
aggregation,  the  disposition  and  character  of  the  spirals,  and 
above  all,  it  gives  the  only  adequate  knowledge  of  the  medullary 
ray  with  respect  to  those  features  which  are  of  the  greatest  value 
m  the  final  differentiation  of  .species.    It  is  true  that  some  of  the 
features  of  the  ray  may  be  inferred  from  a  transverse  and  more 
particularly  from  a  tangential  section,  but  they  cannot  be  utilized 
fully  except  in  generic  differentiations.    The  radial  section  gives 
a  complete  side  view  of  the  ray.  e.xposing  the  entire  structure  in 
all  Its  details  throughout  the  whole  radial  extent.    It  is  from  such 
data  that  we  obtain  our  final  decision  respecting  the  separation 
of  the  first  and  second  sections  of  the  genus  Pinus,  the  differen- 
tiation of  Sequoia,  Libocedrus.  and  Taxodium,  the  recognition  of 
species  wherever  found,  a  differentiation  of  the  Ta.xodiinea.-  from 
the  Cupressinerc ;  and  since  it  exposes  the  entire  structure  in  all 
Its  details,  which  are  presented  chiefly  in  side  view,  it  permits  us 
to  determine  their  relatior-j  to  one  another  and  to  the  activities 
of  the  plant  as  no  other  section  can.    As  features  of  subordi- 
nate value  the  radial  section  completes  our  knowledge  of  the 
bordered  pit,  which  it  presents  in  section  wherever  these  struc- 
tures he  in  the  tangential  walls,  a  distribution  which  may  be 
more  accurately  ascertained  in  this  plane  of  section  than  in  the 
tangential,  smce  they  are  more  certain  to  occur  within  the  limits 
of  a  given  field.    For  similar  reasons  the  radial  section  affords 
the  most  convenient  means  of  studying  the  longitudinal  aspects 
of  resin  passages,  resin  cysts,  resin  cells,  and  crystallogenous 
idioblasts. 


20 


ANATOMY  OF  THK  G\MNOSPERMS 


The  tangential  section,  which  is  also  a  longitudinal  one,  is  such 
as  cuts  a  given  radius  at  right  angles,  and  it  is  .  >)st  completely 
such  in  all  its  parts  when  none  of  the  included  medullary  rays 
are  cut  diagonally.  This  result  is  always  possible  in  stems  of  large 
size  from  which  typical  tangential  sections  of  several  square  centi- 
meters may  be  cut  without  difficulty ;  but  in  small  stems  it  often 
happens  that  only  one  or  two  sections  of  value  can  be  obtained, 
since  the  nearer  the  plane  of  section  approaches  the  center  of  the 
stem  the  more  nearly  does  it  approximate  to  a  radial  section. 
It  follows  from  this  that  in  many  cases  sections  will  have  to  be 
employed  in  which  only  a  limited  area  exposes  the  typical  struc- 
ture, all  the  rest  being  partially  radial.  With  respect  to  the  latter 
it  should  be  pointed  out  that  any  deviation  from  a  strictly  tangen- 
tial plane  will  involve  a  distortion  of  the  structure  of  the  medul- 
lary ray,  and  inasmuch  as  the  value  of  the  latter  for  diagnostic 
purposes  rests  very  largely  upon  the  form  of  the  ray  cells,  it  will 
be  evident  that  even  a  slight  reduction  of  the  angle  from  ninety 
degrees  must  introduce  an  alteration  of  form  which  renders  the 
ray  of  no  value.  The  chief  value  of  the  tangential  section  is 
thus  seen  to  lie  in  its  exposure  of  the  extremities  of  the  rays, 
the  general  composition  and  number  of  which  may  then  be 
ascertained  with  accuracy.  From  this  it  is  possible  to  infer  the 
presento  "f  certain  structures  in  the  tranverse  section,  such  as 
the  resin  passages,  since  as  already  pointed  out  there  are  very 
constant  relations  between  the  occurrence  of  such  passages  in  the 
rays  and  in  the  longitudinal  structure.  Important  exceptions  to 
this  otherwise  general  law  are  to  be  met  with  in  certain  resin 
cysts  of  traumatic  origin  among  recent  plants,  and  also  in  the 
case  of  certain  extinct  species.  Thus  Sequoia  Burgessii  does  not 
exhibit  resin  passages  in  a  transverse  section,  though  they  do 
occur  and  are  characteristically  developed  in  the  medullary  rays. 
Precisely  similar  structural  conditions  are  to  be  found  in  Pity- 
oxylon  chasense.  From  the  recent  studies  of  Jeffrey,  however 
(25),  we  are  led  to  the  inference  that  such  unusual  relations, 
which  at  first  seem  to  indicate  some  peculiar  feature  in  develop- 
ment, may  in  reality  be  due  to  the  fact  that  the  longitudinal  resin 


:1 


OENERAI,  DIRKCTIONS  j., 

passages  occur  at  such  witlc  intervals,  or  arc  so  grouped  within 
narrow  areas,  that  a  given  s|)ec  imcn  may  show  n.^ne  of  them  in 
transverse  section,  although  a  very  considerable  area  is  examined. 
In  a  minor  degree  the  tangential  section  is  also  useful  but  not 
necessary  in  extending  our  knowledge  respecting  the  distribution 
of  bordered  pits  in  the  tangential  walls  of  the  tracheids,  but 
whenever  such  features  are  to  be  studied  critically  it  will  be 
necessary  to  provide  two  cntial  sections  for  each  species, 

one  passing  through  the  spring  wood  and  the  other  through  the 
summer  wood. 

For  the  preparation  of  sections  of  fossil  woods  which  are 
strongly  silicified  or  calcified,  or  otherwise  infiltrated  with  mineral 
matter,  special  apparatus  for  cutting  and  grinding  is  required, 
and  this  part  of  the  work  is  best  accomplished  by  intrusting  it 
to  one  who  has     lined  the  necessary  dexterity  through  long 
experience.    For   those   fossil  woods   of  comparatively   recent 
deposits,  such  a!i  the  Pleistocene  or  later  formations,  which  have 
undergone  little  or  no  modification  by  the  infiltration  of  mineral 
matter,  the  methods  applicable  to  woo<ls  from  existing  species 
will  be  found  to  meet  all  the  requirements  of  the  case.    Where 
there  has  been  a  slight  infiltration  of  mineral  matter,  boiling 
with  sodium  carbonate  will  in  most  cases  serve  to  remove  the 
carbf  nate  or  silicate,  as  the  rase  may  be.  and  bring  the  material 
into  such  condition  that  it  may  be  cut  with  facility  by  the  micro- 
tome knife.    In  all   such  cases,  however,  before  mounting  for 
examination,  care  must  be  taken  to  fully  neutralize  the  action 
of  the  alkah  by  the  action  of  dilute  acetic  acid,  which  serves  to 
restore  the  structure  to  its  normal  volume. 

In  the  case  of  recent  coniferous  woods  it  will  meet  all  the 
requirements  of  the  case  and  amply  provide  for  species  deter- 
mmr.cions  if  blocks  about  one  centimeter  cube  are  boiled  in  water 
from  ore  half  to  two  o-  three  hours  and  then  sectioned  while  hot 
The  "lectnns  should  be  cut  as  thin  as  possible,  carefully  freed 
from  air,  stained,  and  mounted  in  Canada  balsam.  In  thickness 
the  .sections  should  be  as  nearly  as  possible  of  the  diameter  of 
a  tracheid  or  less,  and  this  may  be  accomplished  by  means  of  a 


»3 


ANATOMY  OK  THE  (JYMNOSPKRMS 


carefully  sharpened  pbnc,  which  is,  in  si)mc  respects,  one  of  the 
very  best  of  section  cutters  where  the  work  does  not  call  for  the 
most  critical  methcxls.  Preferably  the  hhx'ks  which  have  Ix-'en 
boiled  as  descrilM.*d  may  Ix:  sectioned  on  a  microtome  in  the 
usual  way.  For  this  pur|)ose  any  instrument  which  provides  a 
high  degree  of  rigidity  may  Ik*  employed.'  For  purfmses  of  very 
exact  study  more  elaborate  methods  and  more  expensive  instru- 
ments will  have  to  be  employed,  but  since  these  relate  chiefly  to 
botanical  laboratories  where  they  are  already  well  known,  they 
ne'".l  not  be  specified  here. 

For  the  put  j  '  -  of  freeing  the  sections  from  air,  a  somewhat 
troublesome  pioccss  where  sections  are  prepared  as  specified, 
the  air  pump  may  be  used;  but  a  far  more  simple  and  less  costly 
method  is  to  boil  the  sections  in  water  for  five  or  ten  minutes  and 
then  plunge  them  directly  into  95  jk-t  cent  alcohol.  At  intervals 
of  five  minutes  or  so  alternate  the  treatment  with  alcohol  and 
water,  and,  except  in  some  of  the  most  troublesome  woods,  such 
as  the  spruces  and  larches,  it  will  be  found  that  the  air  is  all  dis- 
charged in  thj  course  of  half  an  hour.  As  a  matter  of  precau- 
tion the  sections  should  then  be  left  over  night  in  95  per  cent 
alcohol  in  order  to  secure  complete  dehydration. 

Before  mounting  in  balsam  the  sections  must  be  stained.  For 
this  purpose  almost  any  of  the  well-known  aniline  st^in'-  •• 
Delafield's  hematoxylin  may  be  employed,  the  object  being  to 
secure  a  perfectly  sharp  and  wcU-definod  image  on  a  clear  field. 
But  in  tiie  study  of  woods  it  is  often  of  imix)rtance  to  be  able  to 
photograph  what  is  seen,  and  as  all  the  stains  are  not  equally 
valuable  for  this  purpose  the  dye  should  be  selected  with  special 
reference  to  the  results  sought.  Where  instantaneous  exposures 
are  to  be  employed  nothing  is  better  than  Delafield's  hema- 
toxylin, which  is  allowed  to  act  until  a  deep  purple  color  is  pro- 
duced.   But  this  stain  will  not  answer  for  time  exposures  as  well 

>  One  of  the  best  of  simple  instruments  is  the  table  microtome  made  by  Bausch 
and  I,omb,  but  the  knife  used  with  this  form  of  instrument  should  be  a  plane  blade 
mounted  in  a  heavy  wooden  handle  of  such  form  as  to  secure  a  perfectly  firm  grip. 


GENERAL  DIRECTIONS  ,j 

as  some  others.  Under  these  requirements  we  may  employ  a 
stronji  alcoholic  solution  of  Bismarck  brown  which  is  actinically 
o|K.quc.  Hy  its  use  walls  which  are  presented  in  section  do  not 
transmit  enough  light  to  affect  the  plate  evei:  after  rather  long 
exixjsures,  while  those  walls  which  are  presented  in  side  view 
and  are  relatively  of  little  volume  transmit  enough  light  to  make 
a  strong  contrast.  By  using  such  process  plates  as  the  Imperial 
a  well-taken  negative  will  show  sharply  contrasting  black  and 
white  and  will  bring  out  all  the  details.  All  of  the  photographs 
in  the  present  work  were  taken  in  this  way. 

After  staining  the  sections  should  be  passed  into  oil  of  cloves 
until  thoroughly  cleared,  after  which  they  shouU:  k  mounted  in 
xylol  balsam. 


I. 
f 

ii 


CHAPTER  II 

THE  GROUTH   RING 

In  proceeding  to  a  study  of  the  transverse  section  the  first 
feature  to  which  attention  is  naturally  directed  is  the  growth 
ring.  These  are  either  broad  or  tutrrow,  variable  or  uniform, 
eccentric  or  regularly  concentric  according  to  their  relative  pro- 
portions in  radial  extent,  the  constancy  of  their  radial  volume, 
and  their  equal  or  unequal  development  at  all  points  about  a  com- 
mon center.  While  a  recognition  of  such  features  often  serves 
an  important  purpose  in  confirming  data  from  other  sources,  they 
are  in  reality  of  secondary  importance  and  too  much  stress 
must  not  be  laid  upon  them  ;  in  fact,  they  may,  if  necessary,  be 
ent=  '  '  neglected  in  most  cases.  This  clement  of  doubt  is  due 
to  V  that  within  a  given  transverse  section  of  an  entire 

sie.  growth  rings  vary  very  greatly  among  themselves  as 

the  result  of  varying  rates  of  growth  induced  by  external  con- 
ditions of  soil  and  climate.  These  variations  are  of  such  a  nature 
that,  in  general  terms,  the  growth  rings  will  have  the  greatest 
radial  dimension  in  a  young  stem  or  at  the  top  or  toward  the 
center  of  an  old  stem,  while  such  dimension  diminishes  within 
the  same  stem  radially  outward,  so  that  in  the  peripheral  portion 
of  a  very  old  trunk  the  rings  will  be  cither  actually  or  relatively 
very  narrow.  This  general  rule  is  subject  to  many  exceptions. 
In  consequence  of  the  suggestions  furnished  by  this  structural 
feature  it  is  desirable  to  include  its  description  in  every  diagnosis 
of  a  species,  and  we  may  therefore  consider  somewhat  in  detail 
its  principal  aspects  of  structure  and  variation. 

All  of  the  North  American  Coniferales  without  exception, 
both  fossil  and  recent,  and  also  all  of  the  Japanese  species  so 
far  investigated,  are  characterized  by  well-defined  growth  rings. 
These   regularly  recurring   zones   of   growth,  arising   through 

24 


iL^ 


i 


THE  (IROWTH  RING 


25 


alternating  periods  of  physiological  rest  and  activity,  correspond 
very  closely  with  annual  periods,  whence  it  is  possible  to  utilize 
them  in  determining  questions  of  age  which  may  be  ascertained 
in  northern  latitudes  within  an  error  not  exceeding  and  usually 
much  less  than  one  per  cent    (53,    i.._M.    This  law  has  been 
applied  with  success  to  the  deteir.. nation  of  th  ;  probable  age 
of  certain  blazes  found  in  beech  .ree    in  Carad...  tracing  them 
to  the  year  172 1  and  their  probab  r  r,ri  rjn  ,,t  th-,  hands  of  some 
of  the  early  Franciscan  missionaries  (54,  350,  and  55,   500) ; 
while  Campbell  has  similarly  applied  it  to  a  determination  of  the 
age  of  certain  Sequoias  and  the  years  in  which  forest  fires  or 
other  injuries  were   inflicted   (9,   335).     The  chief   sources   of 
error  in  such  estimates  lie  in  the  difficulty  of  clearly  recognizing 
under  all  conditions  the  relation  of  a  particular  growth  ring  to 
a  certain  year,  since  it  is  a  well-known  fact  that  under  peculiar 
conditions  more  than  one  ring  may  be  formed  in  one  season. 
Thus  Penhallow  has  shown  that  while  in  northern  latitudes  there 
is  an  essential  constancy  in  the  relation  of  rings  to  annual  periods, 
this  constancy  diminishes  toward  the  equator  with  a  tendency 
to  the  obliteration  01"  the  growth  rings,  whence  it  follows  that  at 
some  intermediate  point   in  latitude  there  will  be  more  rings 
formed  within  a  given  period  than  there  are  years  of  age  (5^3, 
162).    This   is  supported   by   the  observed  fact   that   in   the 
state  of  New  York  the  common  red  maple  (Acer  rubrum)  has 
been  known  to  form  an  average  of  three  rings  for  each  year  of 
growth,  while  in  Florida  at  least  forty  rings  have  been  found  in 
trees  less  than  thirty  years  old.    In  such  cases  experience  will 
soon  mdicate  to   the  observer   that   the   demarcation  between 
rmgs  of  successive  years  is  much  more  pronounced  than  between 
those  of  the  same  year,  directly  corresponding  to  the  duration 
an-.l  intensity  of  the  rest  periods  in  each  case,  and  from  this 
It  is  possible  to  reduce  the  error  from  such  a  .source  to  a  mini- 
mum.   Thus  De  Bary  has  shown  that  such  double  growth  rings 
as  are  referred  to  are  the  direct  result  of  some  disturbance  of 
the  normal  course  of  growth  for  the  season,  such  as  may  arise 
through  the  operation  of  frost,  drought,  insects,  etc.  (13,  514). 


26  ANATOMY  OF    11  li:  OYMNOSPKRMS 

A  concrete  illustration  of  the  conditions  which  would  be  likely 
to  produce  such  a  result  is  presented  in  a  late  frost  which  seri- 
ously affected  vegetation  in  the  neighborhood  of  Montreal  m  the 
sp.in-  of  1902.    On  the  9th  and  10th  of  May  of  that  year  a  cold 
waveVssedover  Montreal,  and  inflicted  such  serious  losses  upon 
early  crops  and  effected  so  much  damage  to  trees  and  shrubs 
as  to  excite  much  comment.    At  that  time  nearly  all  trees  and 
shrubs  were  in  tender  leaf.    Many  were  either  in  bloom  or  the 
flower   buds -as   in   the  horse-chestnut  -  were   wel    formed 
but  not  open.    In  such  cases  the  new  branches  had  already 
attained  a  considerable  length,  but  in  many  of  the  later  species, 
such  as  Catalpa.  the  English  maple  (Acer  campestre),  sumac 
(Rhus  typhina),  and  the  ash„  the  leaf  buds  were  not  opened  and 
no  material  injury  resulted.    In  all  of  the  earlier  forms,  however, 
the  leaves  and  young  branches  were  killed,  and  in  the  horse- 
chestnut  and  elder  (Sambucus  racemosa)  recovery  involved  the 
formation  of  an  entirely  new  set  of  organs  ^ rom  latent  or  adven- 
titious buds.    In  such  cases  it  is  altogether  likely  that  an  exami- 
nation of  the  wood  for  that  year  would  show  two  rings  of  growth, 
between  which  the  distinction    might  be  expected   to  be  less 
clearly  defined  than  between  those  of  successive  years. 

Variations  in  the  width  and  prominence  of  growth  rings  ot 
successive  years  are  in  some  cases  so  marked  that,  were  pieces 
of  wood  from  the  same  stem  to  be  examined  without  any  knowl- 
ed-e  of   their  previous   relations,  they  might  be  regarded  as 
re^csenting  wholly  different  species.    This  is  notably  the  case 
in  the  hard  pines,  such  as  P.  palustris.  P.  cubensis,  P.  echmata. 
etc    while  it  is  also  true  of  Pseudotsuga  Douglasn,  m  which  this 
feature  has  been  critically  studied.    In  a  large  cross  section  of 
this  wood,  embracing  five  hundred  and  thirty-eight  growth  rings, 
the  latter  were  found  to  be  disposed  in  well-defined  zones,  which 
vary  greatly  in  width,  while  the  component  rings  of  cont^uous 
zones  show  well-marked  differences  in   '"-f  ^  J"^™^",/"  ;"" 
structive  example  of  such  growth  is  given  by  Hartig  (22.  40)  m 
the  case  of  the  Tyrolean  larch,  taken  from  a  height  of  a  thou- 
sand meters  and  having  an  age  of  one  hundred  and  nmety  years 


THE  CROWTH  RING 


27 


though  only  nineteen  centimeters  in  diameter.  Further,  within 
each  zone  (Pseudotsuga)  the  range  of  variation  is  narrower,  and 
oftentimes  the  rings  present  a  remarkable  degree  of  uniformity. 
So  well  marked  arc  these  differences  that  when  a  number  of  trees 
are  examined  it  is  possible  to  establish  an  exact  correspondence 
of  zones  by  means  of  the  average  dimensions  of  the  component 
growth  rings.  These  facts  point  with  some  force  to  the  probable 
operation  of  similar,  if  not  identical,  conditions  of  growth  over  a 
somewhat  extended  period,  while  the  periodicity  of  growth  also 
suggests  a  corresponding  periodicity  in  environmental  conditions. 
It  has  elsewhere  been  shown  (52,  35)  that  in  the  case  of  trees 
exhibiting  four  such  zones  the  following  results  are  obtainable : 


Variations  of  Zones  and  Growth  Rings  in 
Pseudotsuga  Douglasii 


i 


ZUNK  I 

ZUNB  2 

Zone  3 

ZUNR  4 

No.  35 

r  Total  width  of  zone,  cm.       .     . 

•   Number  of  rings 

I  Average  width  of  rings,  mm.     . 

2.12 

s 
4.24 

'5-77 
73 
2.16 

16.48 
141 
1. 17 

0.00 

0 

0.00 

No.  2 

r  Total  width  of  zone,  cm.  .    .    . 
•<  Number  of  rings      .    . 
I  Vverage  width  of  rings, 

0.00 

0 

0.00 

11.95 

SO 
2.38 

452 
38 
1. 19 

0.00 
0 

0.00 

No.  789 

r  Total  width  of  zone,  cm.  .     .     . 

■i  Number  of  rings 

I  Average  width  of  rmgs,  mm.     . 

17.07 
39 
438 

2.85 
10 
2.85 

4-77 

27 

1.70 

1.36 

14 

0.97 

No.  428 

r  Total  width  of  zone,  cm.       .     . 

■j  Number  of  rings 

I  Average  width  of  rings,  mm.     . 

2.72 

8 

340 

16.38 
66 

2.52 

0.70 

4 
I-7S 

0.00 

0 
0.00 

No.  316 

j-  Total  width  of  zone,  cm. .     .     . 

•j  ■ "   -nber  of  rings 

'  .xverage  width  of  rings,  mm.     . 

16.28 

33 
4.96 

4.42 
'7 
2.60 

323 
28 
1.15 

0.85 

10 

0.85 

Totals,  mm 

Averages,  mm 

16.95 

4.24 

12.51 
2.50 

6.96 
«-39 

1.82 

0.91 

28 


ANATOMY  OF  THE  GYMNOSPERMS 


The  variations  thus  indicated  are  usually  accompanied  by  a 
more  or  less  marked  alteration  in  the  relative  volumes  of  the 
spring  and  summer  woods,  in  consequence  of  which  the  same 
tree  may  show  regions  of  coarse-grained  and  fine-grained  wood. 
Plate  I  exhibits  the  characteristic  features  of  such  fine-grained 
wood,  and  a  comparison  with  plate  46  will  serve  to  emphasize 
the  deviation  from  the  usual  type  of  structure. 

Eccentricity  of  the  growth  ring  is  a  feature  more  or  less  com- 
mon to  all  woods  (31,  513).  and  it  is  determined  by  external  con- 
ditions of  light  and  warmth  (22,  41  et  seq.),  but  ordinarily  such 
variations  are  not  sufficiently  marked  to  merit  comment.  In  the 
genus  Juniperus,  however,  eccentricity  is  developed  to  an  un- 
usual extent,  and  it  serves  as  a  more  or  less  distinguishing  fea- 
ture. From  the  photograph  presented  in  plate  2  i.  'be  seen 
that  the  rings  not  infrequently  coalesce  on  one  side,Wi  -c.n- 
ing  great  prominence  as  separate  structures  on  the  opposite  side. 
A  like  eccentricity  characterizes  the  genus  Taxus. 

We  are  then  to  conclude  that  growth  rings  are  a  normal  and 
constant  feature  in  the  stem  structure  of  the  Coniferales  as  a 
whole,  and  the  same  is  also  true  of  the  Gingkoales  so  far  as  we 
know  them  through  both  fossil  and  recent  examples  of  the  genus 
Gingko.    But  the  same  law  does  not  apply  to  the  Cordaitales  as 
a  whole,  and  in  this  may  be  found  one  of  the  leading  distinctions 
between  these  two  groups.    This  is  especially  true  of  the  genus 
Cordaites  in  which  the  "  growth  rings  wnen  present  are  obscure, 
rarely  somewhat  conspicuous,"  and  even  in  the  latter  case  they 
appear  simply  as  regions  of  somewhat  unequally  variable  density, 
dependent  upon  regional  changes  in  the  thickness  of  the  tra- 
cheid  walls  and  the  volume  of  the  lumen,  the  one  region  merging 
into  tae  other   by   somewhat   gradual  transitions  and  always 
without  that  sharply  defined  alteration  of  structure  so  charac- 
teristic of  the  growth  rings  in  the  Coniferales  (plate  i).    In 
existing  Araucarias  the  "  growth  rings  are  not  determinable,  or 
at  most  poorly  defined,"  though  De  Bary  (13,  513)  cites  the  case 
of  a  specimen  of  A.  excelsa  grown  in  the  open  ground,  which 
showed  sixteen  sharply  defined  growth  rings,  and  Kraus  has 


THE  GROWTH  RING 


29 


observed  somewhat  similar  phenomena  in  the  case  of  A.  brasi- 
liana.  Specimens  coming  under  my  own  observation,  but  repre- 
senting growth  which  was  completed  in  a  conservatory,  show  that 
in  A.  excclsa  and  A.  Cunninghamii  the  growth  rings  are  either 
not  determinable  or  at  most  very  imperfectly  defined ;  while  in 
A.  Bidwillii  they  are  only  faintly  defined  by  a  slightly  more  open 
structure  in  the  earliest  spring  wood.  The  same  law  holds  tnie 
for  fossil  species  in  which  it  meets  with  only  partial  exceptions, 
as  in  A.  Edvardianum.  In  Dammara  the  "  growth  rings  are  more 
or  less  clearly  defined,"  approximating  in  this  respect  to  what 
is  found  in  the  Coniferales,  and  between  which  and  the  typical 
Cordaitales  they  may  be  held  to  represent  a  transitional  form. 

Apart  from  those  conditions  of  internal  tension  which  arise 
incidentally  to  the  formation  of  dissimilar  tissues,  and  which 
induce  structural  alterations,  growth  rings  may  be  regarded  in 
the  main  as  a  direct  expression  of  the  alternation  of  sharply 
defined  growth  and  rest  periods  ;  and  since  these  in  turn  are  cor- 
related with  sharply  defined  seasonal  changes,  such  as  are  com- 
mon to  more  northern  latitudes,  it  becomes  possible  to  utilize 
these  facts  in  forming  an  approximate  estimate  of  the  general 
climatic  conditions  under  which  the  tree  must  have  developed. 
From  this  it  is  also  possible  to  draw  important  inferences  as 
to  the  climatic  conditions  which  must  have  prevailed  in  t^.lier 
geological  periods,  as  inc'  :ated  by  the  presence  or  absence  and 
the  specific  charactei  of  growth  rings  in  fossil  woods,  a  conclu- 
sion which  gains  force  from  the  relation  which  the  formation 
of  growth  rings  in  Araucaria  bears  to  climatic  conditions,  as 
already  stated. 

Every  growth  ring  presents  two  structurally  dissimilar  regions 
which  correspond  with  different  periods  of  activity,  and  it  is  the 
apposition  of  these  in  successive  years  which  principally  deter- 
mines the  recognition  of  the  growth  ring.  The  initial  growth  of 
a  given  year  arises  at  the  earliest  possible  moment  at  which  the 
cambium  is  capable  of  generating  new  tissue.  The  elements 
which  thus  arise  are  applied  directly  to  the  outer  face  of  the 
growth  rin-;  for  the  preceding  year.    In  the  formation  of  such 


30 


ANATOMY  OF  THE  (iYMNOSFERMS 


elements  two  important  factors  are  involved.  Owing  to  the 
peculiar  conditions  of  growth  attending  their  organization,  they 
are  formed  under  a  minimum  tension,  in  consequence  of  which 
they  rapidly  attain  to  relatively  great  size,  and  it  is  therefore 
found  that  the  first  tissue  of  the  season  is  always  most  open. 
But  this  feature  depends  again  upon  the  second  factor.  In  con- 
sequence of  the  great  excess  of  nutrition  supplied  during  this 
period  of  growth,  and  the  very  rapid  process  of  construction 
which  follows,  secondary  growth  of  the  walls  is  limited  and  these 
structures  remain  thin,  while  the  lumens  are  correspondingly 
large.  In  transverse  section  such  cells  almost  invariably  show  a 
greater  length  of  the  radial  diameter,  which  is  never  less  than 
the  tangential.  As  growth  advances  there  is  a  slight  but  pro- 
gressive change  whereby  the  secondary  development  of  the  wall 
increases  somewhat  and  becomes  constantly  thicker ;  but  the 
principal  alteration  occurs  in  the  form  of  the  cell  in  such  manner 
that  the  radial  and  tangential  diameters  tend  to  equality.  Such 
thill-walled  structure  is  developed  during  the  first  four  or  si.x 
weeks  of  growth,  and  it  is  therefore  designated  as  spring  wood. 
Toward  the  end  of  the  general  growth  period,  which  has  elsewhere 
been  shown  to  terminate  by  the  second  or  third  week  of  July  for 
about  ninety  per  cent  of  trees  and  shrubs  in  this  latitude  (80), 
the  structural  character  of  the  ring  is  subject  to  more  or  less 
profound  change  as  the  rate  of  growth  diminishes  and  the  inter- 
nal tension  of  the  tissues  increases.  The  isodiametric  form  of 
the  tracheid  is  then  replaced  by  an  extension  of  the  tangential 
diameter  and  a  shortening  of  the  radial  diameter,  the  latter  pro- 
gressing more  rapidly  than  the  former.  This  alteration  is  of  such 
a  nature  that  in  those  tracheids  which  represent  the  last  product 
of  the  season's  growth  the  opposite  tangential  walls  are  closely 
approximated  or  even  in  actual  contact,  while  the  tangential 
dimension  is  sensibly  increased  as  compared  with  tracheids  of 
the  same  row  in  the  spring  wood.  Coincident  with  these  changes 
the  secondary  wall  acquires  an  unusual  prominence,  and  in  many 
of  the  hard  pines,  as  also  in  Pseudotsuga,  it  becomes  so  exces- 
sively thickened  that  the  lumen  is  reduced  to  small  dimensions 


THK  (;ro\vhi  ring 


3« 


and  not  infrequently  is  almost  obliterated.  The  snmuur  xvood 
thus  characterized  is  also  distinguished  by  its  greater  hardness, 
which  in  the  Douglas  fir  imparts  an  almost  flinty  character  to 
the  structure ;  and  commonly  also,  as  exhibited  in  Pseudotsuga 
Douglisii,  Pinus  palustris,  P.  resinosa,  etc.,  by  a  considerable 
amount  of  resinous  matter,  which,  by  reason  of  its  definite  color, 
estabUshes  a  more  or  less  striking  contrast  between  the  two 
regions  of  growth.  It  is  therefore  obvious  that  'he  demarcation 
of  the  growth  rings  depends  upon  t'.e  direct  appLsition  of  spring 
and  summer  woods,  each  of  which  is  characterized  by  special 
structural  and  other  physical  features. 

The  transition  from  the  spring  to  the  summer  wood  is  gradual 
when  there  is  no  sharply  defined  limitation  of  the  two  zones,  but 
the  one  seems  to  merge  into  the  other  by  a  series  of  more  or 
less  insensible  gradations.  This  is  exemplified  in  its  typical  form 
in  the  Cordaitales,  and  among  the  Conifcrales  it  is  a  feature 
of  the  great  majority  of  species.  Under  such  circumstances  the 
internal  limits  of  the  summer  wood  can  be  determined  only 
approximately,  and  they  are  necessarily  established  where  the 
greatest  alteration  of  structure  and  color  occur.  Less  freciuently 
the  transition  is  abrupt,  as  in  the  hard  pines,  notably  P.  palustris, 
or  in  the  Douglas  fir  (plate  i).  There  is  then  a  strong  contrast 
between  the  two  structural  regions.  A  further  variation  of  this 
relation  is  to  be  seen  in  those  cases  in  which  the  somewhat  grad- 
ual transition  from  the  spring  to  the  summer  w\)(k1  is  'followed 
the  next  year  by  a  corresponding  change  to  the  spring  v.ood. 
This  is  of  rare  occurrence  and  is  to  be  met  with  in  only  one  case, 
—  Pinus  Torreyana, — in  which  also  such  double  graduation  seenis 
to  arise  only  in  the  case  of  thick  summer  wood,  since,  when  the 
latter  is  thin,  the  transition  is  abrupt.  Rarely  the  summer  wood 
exhibits  a  zonal  development  whereby  it  becomes  doubled  through 
the  interposition  of  a  zone  of  thin-wallcd  and  rather  large-celled 
tissue.  This  finds  its  typical  development  in  Taxodium  distichum, 
of  which  it  is  a  characteristic  feature.  It  may  also  be  met  with 
occasionally  among  the  higher  Coniferales,  especially  among  the 
hard  pines.    It  ii  a  constant  feature  of  taxonomic  value. 


%t 


1; 


32 


ANATOMY  OF  THE  GYMNOSFERMS 


The  relative  volume  of  t  spring  and  summer  wood  is  subject 
to  wide  variation  not  onh  between  different  genera  and  spe- 
cies but  also  as  between  iduals  of  the  same  species.  While 
this  depends  in  the  first  i  icc  upon  inherent  qualities,  it  is  also 
dependent  to  a  very  larj,  \tent  upon  conditions  of  growth.  In 
Juniperus  and  some  species  of  Cupressus,  as  also  in  Torreya  and 
Taxus,  the  summer  wood  may  constitute  the  bulk  of  the  growth 
ring  and  render  it  impossible  to  determine  where  the  spring  wood 
ends.  The  opposite  e.xtreme  is  to  be  met  with  in  the  genus 
Thuya  and  in  many  species  of  Cupressus,  where  the  summer 
wood  is  reduced  to  from  two  to  si.\  rows  of  tracheids,  which  are  to 
be  distinguished  chiefly  by  their  greater  color  and  shorter  radial 
diameters.  The  Douglas  fir  offers  an  excellent  illustration  of 
such  variations  within  the  limits  of  the  species.  This  is  shown 
by  the  following  data,  taken  from  five  different  trees,  and  also 
by  plates  i  and  46. 


RklATIVE   VC)LIT.MF.S   OF    SPRING   AND    .Sl'M.MF.K    WoODS 


OKl.Wril    Rl.Mis    IN    MlLLLMETHKh 

5< 

Average  Volume 
ofRing 

Slimmer  Wood 

Spring  Wood 

Ratios 

Average  Volume 

Average  Volume 

No.     2     .     . 

I 

1,950 

0.891 

1.059 

1:1. 18 

'•  428     .     . 

•* 

2.725 

I. no 

..6.S 

I  :  1.45 

"  789     •     ■ 

3 

3-^SO 

0-975 

2.27s 

«:«-33 

"     35"  ■   \ 

r    4600 

1.200 

3-400 

I  :  2.83 

"  35'''  ■ ; 

"I       '-455 

0-383 

1.072 

1:2.79 

4 

3°97 

0.791 

2.236 

1:2.81 

"  3>6 

5 

5.100 

0.950 

4.150 

«  :  4-37 

While  it  is  thus  evident  that  estimates  of  relative  volume 
are  of  no  great  value  for  purposes  of  e.xact  differentiation,  they 
nevertheless  do  serve  a  useful  purpose  in  some  instances,  and 
they  should  always  1^.  taken  into  consideration  in  a  diagnosis. 


CHAPTHR    III 


TKACHEIDS 


In  the  Gymnosperms  the  woody  structure  of  the  stem  is  com- 
posed of     'ore  or  less  fibrous  elements  to  which  the  generic 
term  trachcids  may  uC  applied  in  conformity  with  the  definition 
adopted  by  De  Bary  (13,  155),  but  whirh,  for  our  present  pur- 
poses, may  be  described  as  elements  of  indeterminate  or  more 
{jeneraliy  of  determinate  length,  of  either  a  proscnchymatous  or 
parenchymatous  type,  and  ciiaracterized  cliiefly  by  the  presence 
of   bordered  pits.    As  such  tracheids  exhibit   important   varia- 
tions among  themselves,  chiefly  with  respect  to  form,  distribu- 
tion, and  structure,  it  is  necessary  to  distinguish  carefully  between 
the  various  types  entering  into  the  structure  of  the  woody  axis. 
First  of  all  it  is  possible  to  distinguish  between  those  of  the 
proscnchymatous  type  and  those  of  the  parenchymatous  type, 
the  differentiation  being  readily  effected  by  means  of  the  ex- 
ternal form.    Those  of  the  parenchymatous  type  are  to  be  met 
with  in  either  the  medullary  rays,  when  they  may  be  described 
as  ray  trachcids,  or  they  arise  in  series  parallel  with  the  prosen- 
chymatous  elements  with  which  they  are  therefore  mingled  as 
wood  parenchyma,  and  they  are  to  be  dist  .iguished  as  paren- 
chyma tracheids.    A  further  discussion  of  these  forms  will  be 
deferred  until  they  can  be  brought  into  connection  with  the  gen- 
eral structures  of  which  they  form  characteristic  features,  while 
at   this  time  our  attention  may  be  directed  more  particularly 
to  the  tracheids  of  the  proscnchymatous  type.    The  fibrous  tra- 
cheids are  of  two  kinds,  spiral  and  pitted.    The  spiral  tracheids 
are  chiefly  met  with  in  the  proto.xylem  region  of  which  they  are 
characteristic  and  dominant  elements  and  where  they  are  of  in- 
determinate length.    Their  spirals  represent  a  secondary  growth 
of  the   cell   wall,   and  the  latter   is  therefore   devoid  of  pits 


34 


ANATOMY  OF  THE  (lYMNOSPERMS 


except  in  transitional  forms.  Rarely  the  spiral  trachcids  are 
met  with  in  the  secondary  wo<xl  of  which  they  then  constitute 
the  chief  part.  But  in  such  situations  the  spirals  represent 
a  tertiary  prrowth  of  the  cell  wall,  which  is  also  characterized 
by  the  pr(  nee  of  borderec.  pits  in  the  secondary  wall.  Such 
tracheids  are  always  of  determinate  length  and  their  extremities 
are  tapering. 

The  pitted  trachcids  are  exclusively  cicments  of  the  secondary 
wood  of  which  they  constitute  the  dominant  features.  They  are 
of  determinate  length  and  their  extremities  arc  tapering.  Their 
walls  are  characterized  by  the  presence  of  peculiar  pits  which 
belong  to  the  secondary  layer,  and  they  are  devoid  of  spirals 
except  in  the  case  of  Taxus,  Torrcya,  Pseudotsuga,  Larix  ameri- 
cana,  and  Pinus  tacda,  where  the  spirals  represent  the  tertiary 
layer  of  the  wall.  It  follows  that  in  this  type  the  tracheids  are 
characterized  by  the  presence  of  both  .spirals  and  pits.  Before 
proceeding  to  discuss  these  t  ^o  forms  of  tracheids  more  in 
detail,  a  synoptical  view  of  the  tracheids  as  a  whole  may  serve 
to  make  their  relations  more  clear. 


Trachkids.  Elemnts  of  -.  c  :  i.  irical  or  fibrou.s  character,  including 
ve.sseis  and  their  derivatives,  together  with  certain  specialized  forms 
of  a  parenchymatous  type,  the  whole  distinguished  by  the  presence  of 
bordered  pits  upon  their  terminal,  tangential,  or  chiefly  -ipon  their 
radial  walls. 
I.  Wood  tracheitis.  Elements  which  constitute  the  dominant  structure  of 
the  .so-called  wood.    They  are  as  foihnvs: 

a.  Resinous.    Not  structurally  different  from  the   pitted  tracheids,  but 

listinguished  by  the  presence  of  resin,  usually  in  the  form  of  local- 
ized ma.sses  like  transverse  septa  in  the  immediate  vicinity  of 
medullary  rays.    Common  to  the  Cordaitales. 

b.  Spiral.    Characterized  by  the  presence  of  a  spiral  structure  which 

is  typical  of  the  protoxylem  of  all  genera  and  is  of  secondary 
origin  ;  also  of  tertiary  origin  and  typical  of  the  secondary  wood 
in  special  cases,  being  then  accompanied  by  bordered  pits. 

c.  Pitted.    Characterized    by    the   absence  of  spirals   e.xcept   in  the 

special  ca.ses  indicated  in  t>,  and  by  the  uniform  pre.sence  of  bor- 
dered pits  of  .secondary  origin,  chiefly  on  the  radial  walls;  typical 
of  the  secondary  wood  in  all  genera. 


SPIRAL   IKACIlhiUS 


35 


a  Wood  parent hy ma  tracheiih,  Ifsually  xhorl,  cylindrical  cells  with  thin 
walln,  tratiHVcrM  terminal  walls,  and  l)ordered  pits.  Confined  to  the 
higher  Conifcrit. 

a.  I'aienchyma  intikeUs.    Characteristic  of  the  xylem  of  the  higher 

Conifcrif.wiih  which  their  general  direction  of  growth  coincides. 
Found  in  a.s.Hociation  with  thi-  resin  pas.sagcH. 

b.  /iay  traiheiiis.  Characttri/cd  .  v  their  occurrence  in  the  medullary 

rays  with  which  their  general  direction  of  growth  coincides. 

We  may  now  proceed  to  a  more  detailed  consideration  of  the 
structure  and  distribution  of  the  trachcids  thus  classified. 


I 


Spiral  Traciieids 

The  spiral  tracheids  are  so  called  because  of  certain  narrow 
banris  of  secondary  or  tertiary  growth  which  lie  upon  the  inner 
face  of  the  cell  wall  and  take  the  form  of  definite  spirals.  These 
structures  arc  found  to  present  great  diversity  in  the  fi  rm  of 
their  transverse  section,  which,  as  shown  many  years  since  by 
De  Bary  (13,  1 56),  may  vary  from  elliptical  or  round-rectangular 
to  an  almost  quadratic  form.    In  general  terms  they  may  be  de- 
scribed as  ribbonlikc  and  localized  tiiickenings  of  the  cell  wall, 
which  are  designed  for  the  obvious  purpose  of  strengthening 
the  latter.   While  this  purpose  is  not  always  a  prominent  feature 
in  the  Coniferas,  it  may  nevertheless  be  recognized  in  the  struc- 
ture of  the  protoxylem    and  it  is  conspicuously  defined  in  those 
thin-walled  elements  to  be  met  with  among  Pteridophytes  or  in 
the  higher  seed  plants,  notably  in  the  spiral  tracheids  of  Zea,  in 
which  there  is  a  strong  disproportion  between  the  thickness  of 
the  initial  wall  and  the  volume  of  the  cell.    In  more  general 
terms,  therefore,   it  may  be  looked  for  in  succulent  stems  of 
vigorous  growth  rather  than  in  those  of  a  more  woody  character 
and  slow  growth ;  or  it  appears  more  frequently  in  plants  of  a 
primitive  type  of  organization  than  in  those  of  a  more  advanced 
type,  in  which  the  elements  have  experienced  a  more  general 
growth  in  thickness,  and  where,  in  con.    /.lence,  snecial  contriv- 
ances for  support  are  not  demanded.     I-'rom  the  standpoint  of 
development,  therefore,  we  may  consider  that  the  typical  spiral 


36 


ANAIOMY  OF   IHK  (lYMNOSPF.RMS 


of  the  primitive  forms  has  been  lost  through  replacement  by  or 
through  its  being  merged  by  extension  and  fusion  into  a  growth 
which  is  continuous  between  all  points  of  the  cell  wall.  The 
capacity  for  the  formation  of  spirals  is  thus  eliminated  from  the 
greater  portion  of  the  structure  of  the  wood,  though  survivals 
are  commonly  met  with  in  many  of  the  higher  seed  plants,  where 
they  impart  to  the  wcxkI  more  or  less  well  defined  characters  of 
diagnostic  value.  This  capacity  is  also  lost  mo.st  completely  in 
the  greater  number  of  the  Cordaitales,  Gingkoalcs,  and  Coni- 
ferales,  —  indeed,  it  may  be  said  that  for  the  secondary  growth 
of  the  wall  it  is  eventually  lost  in  all  species;  but  the  tendency 
still  survives,  a  fact  made  apparent  by  the  observation  that  in 
certain  species  the  tertiary  layer  of  the  wall  invariably  gives  rise 
to  such  spirals,  which  then  constitute  definite  and  reliable  diag- 
nostic features,  while  in  other  species  they  are  only  imix:rfectly 
formed,  In  all  such  cases  the  spirals  are  to  be  regarded  as  sur- 
vivals, —  as  the  last  phases  of  a  tendency  which  elsewhere  has 
become  completely  obliterated. 

The  origin  of  the  spirals  may  be  traced  to  a  localized  second- 
ary growth  of  the  cell  wall.  They  con.stitute,  in  fact,  the  primi- 
tive form  of  the  secondary  wall  which  later  becomes  modified 
in  accordance  with  altered  conditions  of  growth  in  such  way 
as  to  involve  an  obliteration  of  the  spirals.  Such  changes  are 
features  of  progressive  development,  in  consequence  of  which 
it  is  generally  true  that  such  structures  are  always  most  promi- 
nent and  abundant  in  the  more  primitive  types,  becoming  more 
rare  in  plants  ot  a  higher  type  of  organization  and  development. 
Similar  relations  e.xist  as  between  the  primary  and  secondary 
wood  of  all  known  Gymnosperms,  whence  it  is  possible  to  recog- 
nize the  general  law  that  spiral  tracheids  are  a  feature  of  the 
protoxylem,  to  which  region  they  are  wholly  confined  in  the 
Coniferales  and  Gingkoalcs,  and  almost  strictly  confined  in 
the  Cordaitales,  being,  with  few  exceptions  among  the  higher 
Coniferales,  wholly  absent  from  the  secondary  x)Iem. 

The  direction  of  the  spirals  is  constant  in  most  cases,  being 
right-handed  or  ascending  from  right  to  left  on  the  side  nearest 


SI'IRAI,  TRACHEIDS 


37 


the  observer.    Usually  more  than  one  spiral  is  ilevdopal  in  the 
same  tracheid,  l)ut  it  does  not  follow  that  the  lull  nunilar  will 
be  present  at  all  pjints  throughout  the  len^'th  of  the  traihcicl.  As 
between  different  genera  and  si)eties,  the  numlwr  usually  varies 
from  one  to  four.    This  is  much  less  than  in  the  Angiosperms, 
where  they  may  be  as  many  as  sixteen  to  twenty.    Localization 
also  occurs  in  such  manner  that  the  spirals  often  run  in  series, 
these  latter  being  separated  from  one  another  by  wider  intervals, 
and  as  this  relation  is  subject  to  somewhat  wide  variation  within 
the  same  s|)ecies,  it  follows  that  it  cannot  be  utilized  success- 
tuUy  for  diagnostic  purposes,  although  it  is  quite  jxissible  to  rec- 
ognize and  deHne  and  utilize  the  more  general  differences  of 
distribution  in  the  terms/^zf  and  distaul,  miinerotis  and  approxi- 
mate.   The  variation  in  distribution  above  referred  to  is  largely 
expressed  in  the  fact  that  in  the  tracheids  first  formed  in  a  sea- 
son's growth  the  spirals  will  always  be  most  widely  separated, 
while  those  which  are  formed  later  constitute  a  more  compact 
series.    This  fact  becomes  prominent  wherever  such  structures 
can  he  observed  through  a  considerable  radial  extent  of  wood,  and 
it  is  therefore  particularly  well  shown  in  growth  rings,  though  it 
may  also  be  seen  in  the  protoxylem  region  when  the  latter  is  of 
great  radial  extent,  as  in  Cordaites.    Thu.s  in  Taxus  or  Torreya 
or  Psciidotsuga  it  may  be  seen  that  in  passing  from  the  earli- 
est spring  tracheids  to  the  last-formed  summer  wood  there  is  a 
graduated   condensation  of  the  spirals  whi.  h  agrees  with  the 
relativ,    rate  of  development   in  ihe  tracheids  themselves.    A 
similar  variation  is  to  be  seen  within  the  limits  of  an  individual 
tracheid  in  such  way  that  the  spirals  in  tlu   central  region  are 
more  widely  separated  than  those  nearest  the  extremities.  This 
has  been  adequately  explained  by  De  Bary  (13,  157),  who  has 
shown  the  more  distant  coils  to  result  from  stretching  of  the 
walls  during  the  period  of  very  active  development,  but  subse- 
quently to  the  formation  of  the  spirals;  while  the  condensed 
forms  would  be  an  expression  of  a  .slower  rate  of  growth  in  the 
cells  or  in  special  regions  of  them,  in  consequence  of  which  the 
spirals  more  nearly  retain  their  original  relations  to  one  another. 


38 


ANATOMY  OF  THE  GYMNOSPERMS 


In  the  Coniferales  the  spirals  throughout  the  entire  extent 
of  the  protoxyleni  structure  are  more  or  less  distinct,  though 
there  is  a  more  or  less  definite  tendency  to  coalescence.    Such  a 
tendency  becomes  most  pronounced  in  the  lower  Gymnospcrms, 
being  especially  well  defined  in  the  Cycadaceic  ai.d  the  Corda- 
itaceac.    In  the  former  the  spirals  become  approximated  and 
blend  in  such  a  manner  as  to  definitely  reduce  the  areas  devoid 
of  secondary  grow  th,  which  then  assume  an  elongated  form ;  and 
as  this  latter  diminishes  still  further  in  length,  the  spirals  are 
eventually  replaced  by  a  more  general  thickening  of  the  wall 
through  secondary  growth,  and  definite  pits  arise.  Such  changes 
are  progressive  from  the  protoxylem  radially  outward  through 
the  entire  extent  of  the  secondary  wood,  so  that  there  is  a  defi- 
nite series  commencing  internally  with  typically  spiral  elements 
and  terminating  outwardly  with  typically  pitted  elements,  the 
two  being  connected  by  transitional  forms.    The  same  structural 
alteratidns  may  be  seen  in  Cordaites,  which  offers  a  peculiarly 
mstructive  illustration  of  the  process  because  of  the  regularity 
with  which  the  changes  arise  and  the  extent  of  the  structure  in 
which  they  lie.    As  these  transformations  which  are  completed 
within  the  transition  zone  are  of  great  phylogenetic  importance 
as  well  as  of  taxonomic  interest,  it  will  be  necessary  to  trace 
them  somewhat  in  detail  as  they  appear  in  Cordaites  Brandlingii. 
In  the  protoxylem  region  the  structure  is  wholly  composed  of 
spiral  tracheidb  (plnte  3).    In  the  successive  radial  development 
of  new  trache--  's  .her^  is  a  constant  tendency  to  a  more  uni- 
form thickening  of  the  cell  wall  by  a  secondary  growth.    This  at 
first  finds  expression  in  the  more  compact  arrangement  of  the 
spirals  (plate  4),  which  later  coalesce  at  various  points,  thus  giving 
rise  to  more  localized  areas  devoid  of  secondary  thickening,  and 
hence  to  a  scalariform  structure  in  which  the  general  lines  con- 
form more  or  less  closely  to  the  direction  of  the  original  spirals 
(plate  5).    By  a  further  modification  the  elongated,  thin  areas 
become  converted  into  shorter,  often  isodiametric  areas  substan- 
tially by  a  process  of  division.    A  further  tendency  to  general 
thickening  of  the  walls  causes  the  margins  of  the  scalariform 


SPIRAL    IRACHKIDS 


39 


structure  to  project  from  all  sides  and  extend  over  'he  area  of 
arrested  growth  as  a  lip  which  never  completely  closes  at  the 
center,  where  there  is  left  a  usually  circular,  sometimes  oval  or 
again  lenticular  or  even  oblong,  opening,  and  in  this  manner  the 
bordered  pit  is  formed  (plate  6). 

From  the  statements  so  far  presented  it  may  be  correctly 
inferred  that  the  structural  alterations  which  arise  within  the 
transition   zone   are  subject   to  great  variations,  whereby  the 
change  from  spirals  to  bordered  pits  may  arise  very  gradually 
through  a  broad,  radial  zone,  as  in  Cordaites  Brandlingii,  or  it 
may  take  place  very  abruptly,  as  in  the  modern  Conifera:.    The 
general  tendency  of  such  evidence  is  to  show  that  with  a  higher 
type  of  organization  there  is  a  corresponding  diminution  in  the 
transition  zone  and  an  increased  abruptness  in  the  structural 
alterations.    The  logical  result  of  an  extension  of  this  process 
would  be  the  reduction  of  the  bordered  pit  to  the  condition  of 
a  simple  pit,  and  ultimately  to  its  complete  obliteration.    In  the 
Conifernc  the  reduction  of  the  bordered  pit  to  a  simple  pit  some- 
times occurs  in  the  case  of  medullary  rays  or  even  in  the  case 
of  tracheids  with  very  thick  walls,  but  it  becomes  most  promi- 
nent in  the  Angiosperms,  where  it  is  a  characteristic  feature. 
Instances  also  occur  in  some  of  the  hard  pines,  in  which  the  pit 
is  completely  obliterated.    This  applies  in  particular  to  tracheids 
of  the  summer  wood,  the  walls  of  which  have  become  unusually 
thickened. 

The  relations  to  which  attention  has. thus  been  directed  some- 
what in  detail  have  been  expres.sed  in  more  general  terms  by 
De  Bary  (13,  321)  in  the  statement  that,  "Outside  the  primi- 
tive elements  wider  tracheae  follow.  Their  development  takes 
place  successively,  advancing  from  the  inner  edge  of  the  bundle 
outwards,  and,  as  a  rule,  at  a  time  when  the  elongation  of  the 
entire  part  to  which  they  belong  is  nearly  at  an  end.  The 
thickenings  on  their  walls,  therefore,  have  a  successively  denser 
arrangement ;  dense  spirals  and  annular  tracheae,  then  reticu- 
lated and  pitted  tracheae,  follow  one  another  in  succession  from 
within  outwards,  with  gradual  transitions,  or  with  the  omission  of 


^- 


40 


ANATOMY  OF  THE  GYMNOSPERMS 


one  or  the  other  intermediate  form."  It  is  probably  a  justifiable 
inference  from  the  preceding  facts  that  the  relation  which  exists 
between  the  spiral  tracheids  of  the  protoxylem  and  the  pitted 
tracheids  of  the  secondary  xylem  in  the  Conifers  is,  in  general 
terms  and  from  the  standpoint  of  development,  the  same  as 
that  exhibited  between  the  lower  and  higher  types  of  vascular 
plants. 

Inasmuch  as  specimens  derived  from  fossil  woods  or  from 
recent  woods  which  have  been  employed  for  constructive  pur- 
poses will  almost  invariably  represent  some  portion  of  the  sec 
ondary  wood  only,  it  follows  that  in  all  but  exceptional  cases 
the  spiral  structures  so  far  considered  will  be  entirely  absent 
and  in  those  few  instances  in  which  they  may  occur  the  de- 
termination that  they  belong  to  the  protoxylem  region  can  be 
made  without  difficulty.    It  is  nevertheless  true  that  in  x  few 
genera  definite  spirals  are  to  be  met  with  in  the  secondary  wood 
structure  of  which  they  may  then  be  characteristic  features 
throughout  the  entire  extent  of  the  growth  rings,  or  they  may 
be  more  or  less  localized.    Such  spirals,  which  are  obviously  of 
an  exceptional  nature,  are  features  in  the  development  of  the 
tertiary  wall  of  the  tracheid,  and  they  are  therefore  character- 
istics of  thick-walled  elements.    In  all  their  essential  character- 
istics of  form  and  distribution  they  conform  to  the  laws  which 
gover  .  the  spirals  of  the  secondary  wall,  but  they  show  a  marked 
tendency  to  obliteration  through  degeneration  in  the  relatively 
thicker  walls.    Thus  in  the  genus  Taxus  or  Torreya  such  spirals 
are  common  to  all  the  tracheids  of  the  growth  ring,  but  in  Larix, 
as  a  so  in  Pmus  tneda,  in  both  of  which  the  walls  are  relatively 
thicker,  the  spirals  are  reduced  to  a  vestigial  form,  being  spo- 
radic and  m  the  one  case  distant,  while  in  the  other  case  the 
individual  spirals  are  only  partially  developed.    This  law  is  more 
exactly  md  specifically  illustrated  in  P.seudotsuga,  where  there 
IS  a  sti         contrast  between  the  thin-walled  spring  wood  and 
the  very  thick-walled  summer  wood.    In  the  former  the  spirals 
are  perfectly  formed  and  constant,  and  they  bear  a  very  strong 
resemblance  to  what  may  be  observed  in  the  Taxace^     In  the 


SPIRAL  TRACHEIDS 

latter  case,  however,  the  spirals  are  either  sporadic  anH  estigial 
P.  Douglasu)  or  they  are  often  almost  completely  obliterated 
P.  macrocarpa).  So  well  defined  and  constant  are  these  relations 

that  they  serve  as  an  important  differen 

tial  character  for  the  genus. 
Tracheids  with  spirals  developed  in  the 

tertiary  layer  of  the  wall  are  thus  seen  to 

be  typical  features  of  Taxus,  Torreya,  and 

Pseudotsuga,  while  they  are  also  more  or 

less  distinctive  features  of  Larix  ameri- 

cana  and  Pinus  tzeda. 
In  all  investigated  species  of  Torreya 

there  is  a  rather  wide  variation  in  the 

angle  which  the  spirals  make  with  the 

axis  of  growth,  and  this  becomes  most 

pronounced  in  T.  califomica,  which  gives 

the  lowest  angle  for  any  species  of  either 

Torreya  or  Taxus.    Usually  the  spiral 

has  an  angle  quite  distinct  from  that  of 

the  lines  of  striation  in  the  cell  wall,  but 

in  Torreya  taxifolia  (fig.  i)  the  two  often 

coincide.    The  following  will  show  the  various  details  derived 

from  the  average  of  ten  measurements  for  each  species- 


Fig.  I.  Torreya  TAXIFOLIA. 
Radial  section  showing 
spirals  of  tracheids  and 
bordered  pits,    x  210 


Average 
Angle 

Highest 
Angle 

Lowest 

Extreme 
Range 

Torreya  nucifera    .     . 
Torreya  taxifolia   .     . 
Torreya  califomica    . 

70.5° 

70.4 

46.2 

87.0° 

770 

63.0 

57-0° 

61.0 

30.0 

30-0° 

16.0 

330 

Means 

62.3° 

75-7° 

49-3° 

26.3° 

In  the  genus  Taxus  (fig.  2)  the  spirals  are  rather  close  and  in  two, 
^rely  three,  series.  As  in  Torreya,  they  are  typical  throughout 
the  spring  wood,  but  with  a  pronounced  tendency  to  obliteration 
m  the  summer  wood.    This  tendency  is  subject  to  considerable 


42 


ANATOMY  OF  THE  GYMNOSPERMS 


variation  in  different  species.    In  T.  canadensis  the  spirals  are 

conspicuous  throughout.    In  T.  floridana  they  usually  disappear  in 

the  later  growth,  and  are  wholly  wanting 
in  the  two  or  three  last-formed  tracheids. 
In  T.  brevifolia  they  become  very  imper- 
fect in  the  outer  summer  wood  and  tend 
to  disappear  completely,  only  vestiges 
remaining  in  the  last-formed  tracheids. 
In  T.  cuspidata  the  spirals  are  generally 
absent  from  the  summer  wood,  or  when 
present  are  merely  vestigial.  The  angle 
is  somewhat  greater  —  about  7  degrees 
—  than  in  Torreya,  and  with  respect  to 
certain  species  this  fact  is  apparent  with- 
out special  measurement.  The  four  spe- 
cies appear  to  be  paired  off  in  such  a 
way  as  to  represent  a  mean  difference  of 

,_j  >-n  I  ^  p-^««  about  10.9  degrees  as  between  T.  cana- 
]\i      '  densis  and  T.  floridana  on  the  one  hand. 

Fig.  2.  Taxi  s  brevifolia.  ^^^  "^^  brevifolia  and  T.  cuspidata  on 
Radial  section  showing  the  Other.    In  all  cases  the  angles  of 

b2:edM:s"':'':o^"'  ^^^  ^P--^^'^  --  q-^e  distinct  from  those 
of  the  lines  of  striation.    The  follow- 
ing details  are  based  upon  an  average  of  ten  determinations: 


Average 
Ancle 

Highest 
Angle 

IxtWEST 

Angle 

Extreme 
Range 

Mean  op 
Two 

Tixus  canadensis  .     .     . 
Taxus  floridana     .    .     . 
Taxus  brevifolia    .     .     . 
Taxus  cuspidata    .     .     . 

72.4° 

78.4 

63.0 

66.1 

88.0° 
90.0 
76.0 
87.0 

66.0° 
72.0 
55.0 
45.0 

22.0° 
18.0 
21.0 
42.0 

75-4 
64.S 

Means 

69.9° 

85.2° 

S9-S° 

25.7° 

A  comparison  of  these  results  in  detail  emphasizes  the  fact 
that  the  distribution  of  the  spirals,  as  between  spring  and  sum- 
mer wood,  is  in  direct  harmony  with  the   principles  already 


SPIRAL  TRACHEIDS 


43 


stated,  and  furthermore  that  the  angles  at  which  the  spirals 
develop  do  not  afford  an  adequate  basis  for  generic  differentia- 
tion. It  is  nevertheless  possible  to  recognize  subgeneric  grr  jps 
in  such  wise  that  in  both  genera  a  general  line  of  division  may 
be  established  at  ;o  degrees.  In  the  case  of  Torreya  californica 
the  very  low  angle  of  46.2  degrees  may  be  regarded  as  a  differ- 
ential character  of  specific  value. 

In  the  genus  Pseudotsuga  spirals  are  confined  to  the  tra- 
cheids  of  the  spring  wood.  This  has  a  partial  exception  in 
P.  macrocarpa,  in  which  vestigial  spirals  may  be  observed  in 
the  tracheids  of  the  earlier  summer  wood.  In  this  species  the 
mean  angle  is  70  degrees,  but  the  spirals  are  always  character- 
ized by  lack  of  prominence,  they  are  often  widely  distant,  and 
the  somewhat  extended  areas  within  which  they  are  wholly 
wanting  or  fragmentary  suggests  a  process  of  obliteration.  In 
P.  Douglasii  the  average  angle  is  82  degrees ;  the  spirals  are 
characterized  by  considerable  prominence  and  they  are  also,  on 
the  whole,  close.  In  P.  miocena  the  angle  ranges  from  49  de- 
grees to  83  degrees,  with  a  probable  mean  of  about  65  degrees, 
from  which  it  would  seem  likely  that  this  .species  occupies  a 
position  superior  to  that  of  P.  macrocarpa,  but  this  relation  can- 
not be  determined  with  certainty  on  account  of  the  difficulty 
of  ascertaining  their  distribution  within  the  limits  of  the  summer 
wood.  In  the  genus  as  a  whole  the  angle,  the  prominence  of 
the  spirals,  and  the  closeness  of  the  turns  obviously  possess 
well-defined  differential  value  with  respect  to  the  limitations  of 
the  species. 

Among  the  higher  genera  of  the  Coniferre  only  two  cases  are 
known  in  which  spirals  occur,  but  in  each  the  character  is  of  a 
very  sporadic  nature.  In  Larix  americana  the  spirals  are  fre- 
quently found  in  the  summer  wood,  but  they  are  .so  inconstant 
m  their  occurrence  and  present  such  varying  a.>pects  that  the 
angle  cannot  be  determined.  In  Pinus  taeda,  where  the  walls 
of  the  summer  tracheids  are  very  thick,  rudiments  of  spirals 
may  sometimes  be  seen.  Here  also  it  is  manifestly  impossible 
to  determine  the  angle. 


44 


ANATOMY  OF  THE  GYMNOSPERMS 


Viewing  these  five  genera  collectively,  their  spirals  conform 
fully,  in  their  occurrence  and  relation  to  progressive  develop- 
ment, to  the  general  principles  already  stated,  and  especially 
as  formulated  by  De  Bary.  They  possess  no  differential  value 
of  generic  rank  with  respect  to  Pinus  and  Larix,  but  they  do 
have  such  value  with  res  lect  to  Torreya  and  Taxus  on  the  one 
hand  and  Pseudotsuga  on  the  other,  the  differentiation  resting 
upon  their  occurrence  in  the  summer  wood  in  the  former  and 
their  exclusion  from  that  region  in  the  latter.  Were  any  ques- 
tion to  arise  in  this  connection,  it  could  be  authoritatively  decided 
by  the  definite  association  of  resin  passages  and  fusiform  rays 
in  Pseudotsuga. 

It  only  remains  to  determine  how  far  such  structural  features 
may  be  employed  as  a  basis  upon  which  to  determine  the  general 
phylogeny  of  the  genera.  Between  Torreya  and  Taxus  there  is 
very  little  upon  which  to  base  conclusions  respecting  sequence  in 
development,  and  it  is  apparent  that  both  of  these  genera  have 
attained  to  nearly  the  same  level.  Such  differences  as  do  exist, 
however,  seem  to  point  to  the  relatively  though  slightly  inferior 
position  of  Torreya  as  indicated  by  (i)  the  smaller  angle  in  that 
genus,  and  (2)  the  generally  more  compact  spirals  of  Taxus.  This 
view,  so  far  as  it  possesses  phylogenetic  value,  appears  to  confirm 
the  conclusions  respecting  the  relative  positions  of  these  two  gen- 
era as  already  determined  upon  the  basis  of  external  morphology 
and  stated  by  Eichler  (15,  103). 

It  is  fairly  clear,  from  the  facts  at  hand,  that  all  such  spirals 
as  are  to  be  met  with  in  the  higher  Coniferales  are  to  be  regarded 
as  survivals  of  structures  which  gained  greater  prominence  in 
a  more  primitive  state  of  development  of  the  organism.  They 
do  not,  therefore,  indicate  simple  parallelisms  between  plants 
occupying  a  similar  horizon  in  the  scale  of  development,  but  they 
rather  direct  attention  to  derivation  from  a  common  ancestry, 
and,  as  previously  pointed  out  (59,  255),  they  lead  us  to  the  con- 
sideration that  Torreya,  Taxus,  Pseudotsuga,  Larix,  and  Pinus 
represent  different  branches  of  a  general  phylum,  —  undoubtedly 
also  including  other  closely  related  genera  in  which  the  spirals 


PITIED  TRACHEIDS 


45 


have  been  wholly  obliterated,  —  which  had  its  oigin  at  a  point 
anterior  even  to  such  types  as  Cordaites,  and  therefore  in  a  group 
probably  represented  by  the  Cycadofilices. 


Pitted  Tracheids 

The  pitted  tracheids  may  be  so  distinguished  because  of  the 
invariable  presence  of  bordered  pits  upon  their  radial  and,  under 
some  circumstances  also,  upon  their  tangential  walls.  Such  pits 
belong  to  the  secondary  layer  of  the  cell  wall  in  all  cases.  In 
comparatively  few  instances  such  pits  may  be  associated  with 
spirals  in  the  tertiary  wall,  when  the  two  structures  will  be  found 
so  related  that  while  the  latter  may  overlap  the  former,  the 
orifice  always  lies  between  the  turns  of  the  spirals  (figs,  i  and  2). 
In  their  transverse  aspect  there  is  no  feature  which  may  be 
employed  to  distinguish  the  pitted  from  the  spiral  tracheids.  In 
the  longitudinal  aspect  the  former  differs  from  the  more  primi- 
tive forms  of  the  spiral  tracheid  with  respect  to  length  and 
definite  terminations  in  such  way  that  the  one  is  a  wood  cell 
while  the  other  is  a  vessel,  but  between  he  two  no  sharp  line 
of  demarcation  can  be  drawn,  since,  as  already  indicated,  they 
pass  the  one  into  the  other  by  insensible  gradations. 

All  tracheids  exhibit  the  same  structural  features  with  respect 
to  the  development  and  composition  of  the  wall,  and  as  a  knowl- 
edge of  these  is  antecedent  to  a  correct  understanding  of  certain 
alterations  which  arise  incidentally  to  growth  and  also  to  decay, 
It  will  be  desirable  to  examine  into  the  structure  of  the  wall 
somewhat  in  detail. 

Assuming  the  primitive  form  of  the  cell  to  be  that  of  a  sphere, 
this  form  undergoes  alteration  in  accordance  with  tiie  immediate 
environment  whereby  growth  first  of  all  becomes  excessive  in 
one  direction  coincident  with  the  axis  of  growth  for  the  plant 
as  a  whole,  while  it  remains  practically  equal  in  the  r  dial  and 
tangential  planes  which  cut  the  first  at  right  angles.  From  this 
It  follows  that  while  in  a  longitudinal  aspect  the  tracheid  is 
always  presented  as  a  fibrous  element  with  tapering  extremities, 


46 


ANATOMY  OF  THE  (iYMNOSPERMS 


in  a  transverse  section  it  approximates  more  nearly  to  the  primi- 
tive form  and  thereby  exhibits  a  hexagonal  outline  as  directly 
derived  from  the  circular  by  mutual  compression  of  contiguous 
elements.  As  the  woody  elements  arise  by  division,  their  tend- 
ency at  first  is  to  assume  the  spherical  form  ;  hence  they  split 
away  from  one  another.  But  such  separation  is  never  fully  com- 
pleted ;  in  fact,  it  is  never  developed  to  any  marked  extent  in 
woody  tissues  and  it  remains  localized.  The  separation  is  usu- 
ally confined  to  the  angles  of  the  tracheids,  and  it  results  in  the 

formation  of  intercellular  spaces, 
which  therefore  originate  schi- 
zogenous:',  (fig.  3).  In  the  subse- 
quent uiodification  of  the  wall  by 
secondary  growth  these  spaces, 
when  not  too  large,  are  com- 
monly obliterated  by  infiltration. 
The  presence  of  such  intercellu- 
lar spaces  always  emphasizes  the 
fact  that  what  appears  as  a  single 
membrane  is  in  reality  a  double 
wall,  one  half  of  which  belongs 
to  each  of  the  adjacent  cavil 
In  the  secondary  growth  of  the 
wall  new  layers  are  laid  down 


S.V). 


Fig. 3.     PSEUDOTSUGA     DOUGLASII. 

Transverse  section  showing  the  struc- 
ture of  the  cell  wall:  p.w.,  primary 
wall;  J.70.,  secondary  wall ;  /.?</.,  ter- 
t^ary^wall;    ,...,   intercellular   space,    on  opposite  SideS  of  this /J^Vwary 

wall  (fig.  3),  and  in  their  devel- 
opment they  give  the  dominant  features  of  thickness,  color,  and 
hardness  (fig.  3,  j.w.).  When  brought  into  such  relations  the  pri- 
mary wall,  apparently  lying  between  two  cells,  is  often  designated 
the  intercellular  substance.  The  secondary  wall  not  only  exhibits 
very  variable  development  in  thickness  according  to  the  condi- 
tions of  growth,  as  between  the  spring  and  the  summer  woods, 
but  its  growth  is  also  more  or  less  localized,  and  there  thus  arise 
such  structural  features  as  have  already  been  described  in  the 
spiral  tracheids,  or  such  as  will  be  discussed  more  in  detail  in 
a  subsequent  chapter  under  the  title  of  '•  Bordered  Pits."    Upon 


I'JriKI)    IkACHKlUS 


47 


the  inner  face  of  the  secondary  wall  there  is  what  is  known  as  the 
tertiary  xvall  (fig.  3,  t.w.).  This  is  of  limited  volume  in  the  great 
majority  of  cases,  and  it  is  to  be  recognized  as  a  thin  layer.  It 
rarely  attains  any  prominence  or  contributes  to  the  structural 
variation  of  the  tracheid,  but  in  Taxus,  Torreya,  and  Pseudotsuga 
it  does  follow  the  same  course  of  development  as  the  ""i-condary 
wall  of  the  primitive  tracheids,  and  develops  spirals  which  are 
constant  and  distinctive  structural  features.  Vestiges  of  such  ter- 
tiary spirals  are  to  be  found  a'io  in  I.arix  and  Pinus,  and  wherever 
they  occur  they  arc  to  be  interprete«'  as  representing  a  phase 
in  the  degeneration  of  the  spiral  structure  which  has  already 
permanently  disappeared  from  the  secondary  wall  but  survives 
in  the  tertiary  wall  to  a  certain  extent.  In  any  transverse  sec- 
tion of  a  thick-walled  tracheid,  under  favorable  conditions,  we 
may  observe  fine  lines  disposed  concentrically  with  one  another 
and  with  the  primary  wall.  These  represent  the  stratijication 
of  the  secondary  wall,  and  they  are  substantially  due  to  the 
process  of  upbuilding  by  successive  layers.  In  a  longitudinal 
aspect  the  wall  also  shows  a  series  of  fine  lines  cutting  the  axis 
of  the  tracheid  and  the  lines  of  stratification  diagonally,  or  in 
a  transverse  section  cutting  the  latter  radially.  These  repre- 
sent the  lines  of  striation,  due  probably  to  localization  of  water 
of  organization  along  definite  planes  of  growth.  They  are  not 
readily  obser\-able  under  ordinary  conditions,  but  when  the  cells 
are  macerated  in  potassium  hydrate  they  stand  out  with  great 
prominence,  and  it  will  be  seen  in  a  subsequent  chapter  that 
the  same  effect  is  also  produced  by  decay. 

The  substance  of  the  cell  wall  consists  primarily  of  cellu- 
lose, represented  by  the  formula  CgHjoOj,  but  in  the  course  of 
growth  alterations  arise  through  the  introduction  of  carbo- 
hydrate bodies  of  various  kinds,  so  that  the  composition  can  no 
longer  be  represented  by  such  a  simple  formula.  Thus  in  the 
primary  cell  wall  there  is  usually  a  large  amount  of  pectin,  which 
may  be  differentiated  and  localized  by  ruthenium  red,  which 
develops  a  bright  cherry  or  rose-red  color  and  affords  a  very  deli- 
cate test.    In  the  secondary  walls  also  the  cellulose  represents 


4«  ANATOMY  OF  THE  GYMNOSPERMS 

various  modifications  which  may  all  be  embraced  under  the  com- 
prehensive  term  lignin.    Such  lignification  is.  i„  general  terms, 
characterrsfc  of  the  woody  tissue  of  all  plants  in  various  degrees 
but  usually  m  such  manner  that  the  hardness  of  t'  ,  parts  is 

thus  briefly  md.cated  not  only  bear  an  important  relation  to  the 
action  of  various  chemical  reagents  and  stains,  but  they  are 
of  the  first  importance  in  explaining  the  variable  phenomena  of 
decay;  since  it  is  found  that  neither  chemical  agents,  stains,  nor 
decay  act  uniformly  upon  all  parts  of  the  cell  wall,  their  action 
varying  according  to  locality  as  well  as  according  to  the  particular 
agent  or  the  specific  organism  concerned.    It  will  therefore  be 
profitable  to  inquire  somewhat  more  closely  into  these  relations 
According  to  Weiss  (75.  6.)  the  percentage  composition  oi 
the  unaltered  cellulose  may  be  taken  as  C,,.,H,.,,0«3,.   In  the 
course  of  growth,  however,  alterations  of  varbus  Sds  arise 
through  the  introduction  of  carbohydrate  bodies  of  various  kinds, 
though  all  belonging  to  the  cellulose  group,  so  that  the  com- 
position can  no  longer  be  represented  by  such  a  simple  formula 
as  that  given.    The  composition  of  these  secondary  products  or 
incrusting  substances,  though  somewhat  widely  different  in  dif 
ferent  plants  may  be  said  to  vary  within  an  approximate  percent- 
age range  of  5.99  for  carbon,  0.53  for  hydrogen,  and  S.ic  for 
oxygen,  while  their  mean  composition  may  be  stated  as  C  50  7 
H  6.08,  O  43.03  per  cent.    On  the  other  hand,  the  incrustation 
substance  from  the  same  plant  (Fagus  sylvatica)  may  be  found  to 
vary  from  C  48. 10.  H  6.09,  O  47.81  per  cent  to  C  67  91.  H  6  89 
O  25.20  per  cent.    A  comparison  of  these  modified  forms  with 
normal  cellulose  brings  out  the  important  fact  that  while  there  is 
essentially  no  change  in  the  percentage  proportion  of  hydrogen, 
the  oxygen  has  been  reduced  in  varying  quantities  from  fsr 
per  cent  to  24.18  per  cent  with  a  corresponding  increase  in  the 
relative  proportion  of  carbon. 

Accompanying  changes  of  the  nature  thus  far  discussed - 
the  formation  of  the  secondary  h  ;  and  the  deposition  of  lignin 
substance  -  are  always  associated  with  the  deposition  of  mineral 


PirrED  TRACHEIDS  .„ 

49 

matter  which  is  localized  in  the  .ell  walls  as  the  only  way  pro- 
vided for  the  disposal  of  waste  matter.  Such  mineral  salts  are 
important  factors  in  imparting  an  increased  specific  gravity  and 
a  greater  element  of  hardness  to  the  structure  as  a  whole,  while 
they  appear  upon  combustion  in  the  form  of  an  unoxidizable  ash 
residue,  which  varies  in  the  North  American  Conifcrx  from  008 
per  cent  m  Libocedrus  and  Pseudotsuga  -  in  specific  cases  of 
the  latter  falling  as  low  as  0.02  per  cent -to  ..34  per  cent  in 
Torreya  taxifolia  (M,  333). 

The  variations  in  the  cell  wall  thus  noted  are  accompanied 
and  more  or  less  exactly  indicated  by  the  reactions  of  the  wall 
toward  chemical  reagents  and  stains.    Thus  aniline  chloride  or 
sulphate  imparts  a  brilliant  yellow  color  to  the  entire  lignified 
membrane,  serxing  at  the  same  time  to  differentiate  the  primarv 
from  the  secondary  walls  by  virtue  of  the  greater  depth  of  color 
and  the  greater  degree  of  translucency  imixirted  to  the  former 
lodme  IS  absorbed  with  great  energy  by  all  parts,  but  rather  more 
strongly  by  the  primary  wall,  which  thereby  acquires  a  deeper  yel- 
low or  yellowish  brown.    When  lignified  membranes  are  treated 
with  strong  sulphuric  acid  the  secondary  wall  is  attacked  and 
brought  into  solution,  while  the  primary  wall  is  left  intact  if  the 
action  be  properly  limited.    In  this  case  the  action  is  one  of 
hydrolysis.    On  the  contrary,  a  strong  oxidizing  agent,  such  as 
bchulzes  maceration,  acts  first  upon  the  primary  wall,  thereby 
separating  the  secondary  walls  from  one  another ;  or,  in  accord- 
ance with  Mangin's  reaction  with  alcohol  and  hydrochloric  acid 
whereby  the  pectic  acid  is  set  free  from  its  original  combinations' 
It  IS  possible  not  only  to  secure  a  more  intense  reaction  with 
ruthenium  red  but  also  to  separate  the  cells  from  one  another 
when  the  pectic  acid  has  been  neutralized  by  ammonia.    Similar 
disintegrations  may  be  effected  in  the  primary  wall  by  other 
reagents,  m  which  case  they  constitute  the  scientific  basis  for 
such  important  economic  processes  as  are  involved  in  the  manu- 
facture of  wood  pulp  by  chemical  means. 

The  total  thickness  attained  by  the  cell  wall  necessarily  varies 
as  between  the  spring  wood  and  the  .umraer  wood.  This  relation 


r 

r 


50 


ANATOMY  OF  TH'.  »iYMNOSl'KRMS 


is  subject  to  somewhat  wide  varuli  n  as  between  different  spe- 
cies and  genera,  and  it  is  also  funud  to  be  of  a  marked  nature, 
even  in  the  same  species  untier  »!■  twicnt  conditions  of  growth. 
For  more  extended  details  roferen'  c  slioild  be  made  to  the  table 
in  Appendix  A,  but  for  our  present  pui  i .  >ses  a  few  examples  may 
be  selected.    Thus  in  all  three    '^  investigated  species  of 

Araucarb  the  ratio  of  the  walls-    spri-i^  to  summer  wood is 

I  :  I,  a  relation  which  exactly  .  ><  p    ,  with  the  absence  of 

growth  rings.  In  Juniperus  vir^ji  i.u,.i  th.  ratio  is  i  :  2  ;  in  Cryi>. 
tomcria  jaix)nica  it  is  1:4;  in  Isu  -  Si  lx>ldii  it  is  1:5.  On 
the  other  hand,  the  same  sfK'ciesj  '..  \i\'  t  two  ratios  as  deter- 
mined by  the  peculiar  condition!  .,'  ei.u'-t  >,  .ider  which 
the  growth  has  been  formed.    '!  u  -  n  Tax  1 .    anadensis  we  may 

4.fc 
8 
2.4 


*'^^'*^  4'8J  =  '♦^  '*'  '"  ^"^  Lp  ''  f  ^       "^     «*;  and  in  Libo- 

M-    \Mn!o,  therefore,  it  is 


4.8 


cedrus  decurrens  we  may  get  1.4 

obvious  that  there  are  certain  ratio  differences  between  the  walls 
of  these  two  structural  regions, -- differences  which  are  more  or 
less  directly  associated  with  sjxicics,  —and  while  such  differences 
may  be  of  some  value  in  tonfirming  conclusions  derived  from 
other  data,  they  are  not  of  such  a  nature  as  to  permit  the  formu- 
lation of  a  general  law  applicable  to  species  in  such  a  way  as  to 
establish  a  precise  differentiation,  since  variation  arises  within 
the  same  species  as  a  result  of  different  internal  and  external 
conditions  of  growth,  such  as  tension,  soil,  and  climate,  the  lat- 
ter being  influenced  by  situation  and  exposure.  In  many  cases, 
where  the  actual  thickness  of  the  walls  is  the  same,  the  apparent 
thickness  will  vary  considerably.  This  is  directly  attributable 
to  differences  in  the  transverse  volume  of  the  tracheid,  whereby 
the  spring  tracheid,  from  its  greater  size,  will  have  a  wall  rela- 
tively thinner,  and  thus  apparently  thinner  than  that  of  the 
summer  wood.  Our  investigations  show  that  for  twenty  genera 
and  one  hundred  and  fourteen  species  the  mean  ratio  is  1:2.12. 
The  following  summary  for  genera  may  be  consulted  in  this 
connection  : 


I'llTLD   IkACHKlUS 
Tahik  Of  Ratios  rou  the  Tracheiu  Walls  — Gknr 


5i 


KA 


VoiiiMI  .,r  TR*<'Miti>,  _                                       I 

8lMH*K      T.r      •.KMlwCi  "''""^""•'I'WaIH,  L,     „„ 

W.».i.mTK.vv,,„i  Sr».-..i  TO  Slmmhi.    '*"•»"'•"''""" 

ttKTHiN            ^»«»»  Wi«m                                 I'""'  AviiAuar 


Danimara 

Arauiukria 
(•iiigko 

I'lrreya 

i  .ixus  . 
ThujopMS 
Cryptoiii^ria 
Podocarpus 
Taxodium 

Ubocednu 

Thuya  .  . 
Se()uoia  . 
Cupressus 
Juniperus 
Abies  .  . 
Tsuga  .  . 
Pseiidotsuga 
I^rix  .  . 
I'icea  .  . 
f'inus   .    . 


(■rand  average 


I:  1^ 
I  :i.lO 

1:3.64 
I  :  1.62 
I     1.67 

'I  13 
1:1.68 
I  :  2.01 
1:1.25 

1:2.60 

1 :2.26 
1:2.51 
I  :l.98 
1:2.24 

':2-3S 
'  '-97 
-3' 
2.76 

2.12 
1.98 


1:1.66 
I  :  1.00 

'•'33 
1 :  1.99 
1 :  1.56 
I  :2.S0 
I    4-00 

•  :  '43 

■ :  J.OO 


I 

3 
I 

3 
4 
I 
I 
I 
I 


1 :1.9s 


•1:1.70-1 

l«:3-43J 

I 

I  :  2.88 

3 

1:2.75 

2 

1:1.71 

y 

I  :  1.41 

II 

1:2.27 

II 

i:3.or 

5 

I  :  2.95 

2 

I  :  2.86 

4 

I  :  2.27 

9 

1:1.97 

41 

1  :2.I2 

114 

Variations  in  the  transverse  volume  of  the  trachcid  as  ex- 
prcs.sod  in  square  microns  constitute  the  most  prominent  feature 
of  any  tran.s  crse  sc*  tion.  They  are  expressed  most  conspicuously 
between  thv  .spring  and  summer  woods,  and  thex  are  due  to  the 
sanu  causes  which  operate  in  the  formation  of  the  rin^,^  itself. 
Their  relations  are  such  that  the  earliest  spring  tracheids  are 
alwrivs  of  greatest  volume,  but  there  is  a  progressive  diminution 
radially  outward  at  a  somewhat  uniform  rate.  At  a  certain  point 
in  radial  develonment.  however,  there  wul  usiiall)  ix  found  a  some- 
what more  m.-.^ied  alteration,  which  in  specific  cases  becom. 
most  pronounced  — Pinus  palustris  -  and  results  in  an  abrupt 
tran.siiion  from  one  zone  to  the  other.    In  other  cases  —Tax-as 


M 


52 


ANATOMY  OF  THE  GYMNOSPERMS 


and  Torreya  (plates  20  and  22)  — the  transition  is  so  gradual 
that  it  is  often  difficult  or  impossible  to  establish  the  exact 
boundary  between  the  spring  and  summer  woods.  Such  dimi- 
nution in  volume  is  accompanied  by  alteration  of  the  two  axes 
in  such  a  manner  that  the  tangential  is  steadily  lengthened 
whUe  the  radial  is  correspondingly  shortened.  It  is,  therefore, 
commonly  found  that  in  the  last-formed  cells  of  the  season  the 
tangential  diameter  is  somewhat  longer  in  accommodation  to  the 
increased  circumference  of  the  zone,  while  the  radial  diameter 
is  so  shortened  that  the  opposite  walls  are  closely  approximated 
or  even  in  direct  contact. 

The  relative  volume  of  the  spring  and  summer  tracheids  is 
subject  to  somewhat  wide  variation  within  the  limits  of  the 
genera,  being  in  the  ratio  of  i  :  i.io  for  Araucaria,  where  there 
is  practically  no  distinction  of  the  two  zones,  and  of  i  :  3.64  in 
Gingko,  where  there  is  a  correspondingly  sharp  definition.    The 
mean  ratio  for  twenty  genera,  represented  by   1 14  species,  is 
I  :  I.9S-    Within  species  limits  similar  variations  arise,  the  most 
marked  extremes  being  represented  by  Sequoia  and  Juniperus 
In  the  former  case  the  ratio  varies  from  i  :  1.77  in  S.  gigantea 
to  r :  3.26  in  S.  sempervirens.    In  the  latter  genus  the  variation 
lies  between  i  :  1.33  in  J.  conjugens  and  i  :  4.4  in  J.  sabina     A 
somewhat  extended  study  of  the  Douglas  fir  has  given  an  oppor- 
tunity to  examine  these  differences  with  respect  to  a  somewhat 
wide  range  of  individuals.    Thus  in  seven  specimens  taken  with- 
out special  selection,  the  following  values  are  found : 


.  r. 

1:1.91 

2. 

I  :  2.83 

3- 

1:1.14 

4- 

'  :  3.23 

S- 

I  :2.io 

6. 

1:1.92 

7- 

1:2.14 

8. 

1:2.50 

9- 

:  1.70 

10. 

:  2.6f: 

:  1.91  > 

:  2.83  I  ^^g'O"^  variations  in  tlie  same  specimen. 


Regional  variations  in  the  same  .specimen. 


Regional  variations  in  the 


same  specimen. 


RESINOUS  TRACHEIDS 

The  mean  ratio  for  all  these  specimens  is  ,  :  2.2,,  which  very 
closely  approximates  to  that  for  P.  macrocarpa  (r  :  2.4,).  and  it 
shows  that  the  spring  tracheid  is  normally  twice  the  vo  ume  o 
the  summer  trache.d.    But  such  a  ratio  is  subject  to  importan 
exceptions  w.thm  the  limits  of  the  individual.    Thus  the^ate 
for  I  and  2  relate  to  regional  differences  in  the  same  specimen 
and  the  same  as  also  true  c^  5  and  6,  and  9  and  ro.     It^  there! 
ore  obvious  that  such  variations  are  in  no  sense  of  specific  value 
for  diagnostic  purposes,  since  they  are  often  as  widely  divergent 
withm  the  hmits  of  the  species  as  between  different  spedes 
bemg  determined  by  peculiar  conditions  of  growth.    Inasmuch  as 
v^ria  ions  m  the  relative  volume  of  the  tracheids  is  a  feature  o 
he  density  of  the  wood  as  a  whole,  it  may  be  supposed  to  bea 
a  certain  j^lat.on  to  the  strength  of  material  and  so  to  the  value 
of  the  wood  for  constructive  purposes,  but  this  has  been  shown 
not  to  be  the  case  (52,  39). 


Resinous  Tracheids 

In  Araucaria  excelsa  a  transverse  section  shows  more  or  less 
numerous  elements  containing  resin.    These  are  not  to  be  dis- 
tinguished in  their  general  structure  from  the  surrounding  tra- 
chcds.  and  they  are  to  be  recogi.ized  solely  by  their  contents 
which  are  usually  somewhat  prominent.    Their  distribution  is 
characteristic.    They  occur  in  small,  scattered  groups,  or  more 
commonly  in  rows  one  or  two  elements  wide,  parallel  with  the 
medullary  rays  and  in  immediate  contact  with  them  on  each 
side.    When  the  plane  of  section  passes  near  the  po.sition  of 
apparently  terminal  walls,  the  latter  are  cut  through  in  various 
ways   but  they  never  exhibit  any  structural  features,  and  they 
are  therefore  ,n  no  way  comparable  with  the  terminal  walls  of 
he  wood-parenchyma  cells.    In  a  radial  section  these  elements 
are  seen  to  be  long  and  fusiform,  exactly  resembling  the  wood 
tracheids  except  for  reddish-bro^vn,  transverse  plates  which  occur 
ether  close  to  or  exactly  opposite  a  medullary  ray, -a  posi- 
t.on  which  IS  more  clearly  seen  in  a  tangential  section  (fig  4) 


^  :  iii 
i    ■ 


54 


ANATOMY  OF  THE  GYMNOSPERMS 


The  dark  plates  closely  resemble  Sanio's  bands,  for  which  they 
might  very  readily  be  mistaken  upon  casual  observation,  or  they 

might  likewise  be  mistaken  for  terminal 
and  unpitted  walls.  In  Dammara  australis 
these  features  are  presented  in  their  typ- 
ical form.  The  transverse  section  shows 
such  elements  to  be  numerous  and  dis- 
posed in  radial  rows  on  each  side  of  the 
medullary  ray  (fig.  5).  In  a  radial  section 
they  present  the 
same  fibrous  and 
fusiform  charac- 
ter as  in  A  u- 
caria,  but,  in 
addition,  the  wall 
usually  experi- 
ences a  marked 
increase  in  sec- 
ondary growth 
within  the  region 

exactly  opposite  a  ray  (fig.  6).   This  fea- 
ture is  also  prominent  in  the  transverse 

section  (fig.  5).    Such  local  increase  in 

thickness  always  arises  in  adjacent  cells 

in  such  a  way  that  the  more  strongly 

thickened  regions  are  exactly  opposite, 

and  they  serve  to  constrict  the  cell  cavity 

gradually  from  above  and  below,  in  such 

manner  as  to  leave  a  channel  about  half 

the  usual  width  of  the  cell  cavity,  which 

gradually  widens  upward  and  downward 

(fig.  6).  It  is  at  the  position  of  maximum 

constriction  that  we  find  a  transverse 

plate  of  variable  thickness,  but  always  of  a  reddish-brown  color. 

These  plates  are  always  thinnest  in  their  central  region,  and  they 

may  be  of  uniform  thickness  for  the  greater  part  of  their  extent. 


Fig.  4.  Dammara  austra- 
lis. Tangential  section 
showing  the  relation  of  the 
resin  plates  and  the  medul- 
lary ray,  and  a  fractured 
plate  (r./.).    x  225 


Fig.  J.  Da.mmara  austra- 
l.is.  Transverse  section 
showing  the  '  isposition  of 
the  resinous  tracheids  on 
opposiie  sides  of  the  med- 
ullary ray  at  r.t.     x  300 


RESINOUS  TRACHEIDS 


55 


At  the  region  of  contact  with  the  trachcid  wall  they  become 
thicker  and  thereby  attain  a  vertical  distribution  to  an  extent 
four  or  five  times  greater  than  the  general  thickness.    At  such 
position  also  there  is  a  somewhat  clear  differentiation  between 
the  plate  and  the  wall  of  cellulose  in  point  of  color.    Such  plates 
show  absolutely  nothing  of  the  nature  of  pits,  and  they  are  in  no 
sense  comparable  with  the  terminal  walls  of  the  wood-parenchyma 
cells,  except  in  form  and  position  (fig.  6).    The  peculiar  position 
of  these  plates,  their  resinous  color,  and  their  simulation  of  both 
Sanio's  bands  and  terminal  walls  excited  a  suspicion  as  to  their 
true  nature,  and  led  to  the  belief 
that  they  might  not  be  structural 
features  at  all.  They  were  there- 
fore subjected  to  a  series  of  care- 
ful tests  to  determine  (i)  if  they 
were  structural,  (2)  if  they  were 
resinous,  and  (3),  if  the  latter, 
to  what  extent.    It  was  recalled 
in  this  connection  that,  although 
f'evoid  of  any  special  secretory 
reservoirs  in  the  wood,  Dammara 
is  nevertheless  well  known  for  its 
production  of  the  resin  known  as 
kauri  or  gum  dammar.  It  was  sus- 
pected that  the  plates  might  be 
local  deposits  of  resin,  and  they 
were  therefore  brought  into  direct  comparison  with  gum  dammar, 
the  characteristics  of  which  are  well  known  and  described  by 
VVittstein  (77,  63).    Tests  were  applied  to  thin  radial  and  tan- 
gential sections,  employing  for  this  purpose  (i)  various  essential 
and  fixed  oils,  (2)  ether,  (3)  alcohol,  (4)  ammonia,  (5)  potassium 
hydrate  in   ij  per  cent  solution,  and  (6)  concentrated  cupric 
acetate.    The  plates  were  found  to  be  very  refractory  with  re- 
spect to  all  these  reagents,  and  in  all  cases  no  change  was  to 
be  observed,  even  after  the  action  had  extended  over  a  period 
of  several  weeks,  except   partially  in  the   case  of  ether  and 


Fig.  6.  Dammara  australis.  Radial 
section  siiowing  the  local  thickening 
of  the  tracheid  wall,  and  the  occur- 
rence of  resin  plates  (r./.)  opposite 
a  medullary  ray.     x  225 


%i 


56 


ANATOMY  OF  THE  GYMNOSPERMS 


r/>. 


alcohol,  and  completely  in  the  case  of  potassium  hydrate.  In  the 
ether  reaction  there  did  appear  to  be  a  certain  diminution  in 
volume,  apparently  tlirough  solution,  when  the  reagent  was  first 
applied,  but  after  that  there  was  no  further  alteration.  The 
application  of  alcohol,  both  in  the  hot  and  in  the  cold,  showed 
that  while  the  resiu  contained  in  the  medullary  rays  was  all 
dissolved,  the  plates  were  only  partially  affected.  The  reaction 
of  the  reagent  was  chiefly  manifested  in  the  development  of 
strong  curvature,  often  accompanied  by  fracture  (fig.  4,  r.p). 
This  was  evidently  due  to  an  increase  in  volume  as  the  first  tend- 
ency toward  solution,  and  it  gave  the  first  definite  evidence  that 
the  plates  could  not  be  of  a  cellulose  character.    Beyond  this 

no  further  change  was  brought 
about,  even  after  several  weeks 
of  action.    The  potassium  hy- 
r/>     \  drate  gave  the  most  positive 

results.  At  first  there  was  no 
apparent  change,  but  after 
an  interval  of  about  ten  days 
or  two  weeks  the  plates  were 
found  to  have  completely  dis- 
F1G.7.  Dammara  AusTRALis.  Radial   appeared,  leaving  a  perfectly 

section  showing  the  origin  of  the  resin       ,  ,  ,  •     .,  ,.         . 

plates  (r./>.).    x  225  ^^^^^  Channel  m  the  cell  cavity. 

A  further  proof  of  the  resinous 
character  of  these  plates  is  to  be  found  in  the  ruptures  which 
they  not  infrequently  exhibit  (fig.  4,  r./>.),  and  in  the  various 
developmental  stages  which  may  be  observed  without  difficulty 
(fig.  7).  These  show  that  the  resin  gathers  locally  upon  the 
inner  face  of  the  tracheid  wall,  and  as  its  volume  increases  it 
projects  from  all  sides  toward  the  center,  where  it  coalesces 
to  form  a  continuous  and  imperforate  septum.  The  facts  thus 
obtained  prove  most  conclusively  that  the  plates  are  not  cellu- 
lose, and  although  immersion  in  concentrated  cupric  acetate  for 
eight  weeks  failed  to  develop  the  characteristic  reaction,  they 
point  to  the  idea  that  the  plates  are  probably  resinous.  The  con- 
clusion is  probably  justifiable  that  they  consist  of  gum  dammar, 


RESINOUS  TRACHEIDS  57 

which  they  closely  resemble  in  many  of  their  reactions,  but  of  a 
highly  refractory  and  modified  character.  The  same  evidence  also 
conclusively  shows  that  the  cells  in  which  the  plates  are  devel- 
oped  are  normal  wood  tracheids  and  not  wood  parenchyma,  which 
IS  altogether  unknown  in  any  of  the  Cordaitales.  Any  transverse 
section  of  the  wood  of  Cordaites  will  show  these  resinous  plates 
to  be  present,  usually  in  much  larger  numbers  than  in  either 
Dammara  or  Araucaria.  and  they  exhibit  the  same  features  in  dis- 
tribution (plate  12).    Compare  also  plates  14  and  16 

We  are  naturally  led  to  ask.  What  is  the  purpose  of  these  resin 
pbtes?    The  peculiar  form  in  which  the  resin  is  deposited  and 
the  particular  location  of  the  plates  points  with  much  force  to 
their  connection  with  some  functional  activity,  since  if  it  were 
simply  a  question  of  the  storage  of  secreted  products,  the  latter 
would  hardly  be  disposed  as  found,  but  rather  after  the  manner 
common  to  so  many  of  the  Cupressine^;  and  this  suggestion 
gams  strength  from  the  fact  that  with  respect  to  the  peculiar 
form  of  the  resin  masses  as  well  as  their  location  in  the  tissue 
the  Cordaitales  are  peculiar  among  the  Gymnosperms.  No  exact 
comparison  can  be  established  with  other  plants,  and  it  is  diffi- 
cult to  suggest  an  adequate  explanation.    One  thing  does  seem 
clear,  however,  and  that  is  that  since  these  plates  are  of  an 
impervious  nature  and  developed  in  some  cases,  at  least,  in  con- 
nection with  a  special  constriction  of  the  tracheid  cavity,  they 
offer  and  possibly  are  specially  designed  to  afford  a  definite 
obstruction  to  circulation  in  a  vertical  direction.    In  this  sense 
they  may  be  designed  to  serve  the  same  general  purpose  that  is 
accomplished  by  the  development  of  thyloses  in  the  vessels  of  the 
Angiosperms  or  in  the  resin  passages  of  the  higher  Coniferales 
It  IS  therefore  possible  that  they  may  be  connected  in  some  way, 
not  at  present  clear,  with  a  more  complete  restriction  of  the 
circulation  to  a  horizontal  direction,  and  particularly  through 
the  medium  of  the  medullary  rays  as  specialized  channels  for 
that  purpose.    Among  existing  Gymnosperms  resinous  tracheids 
are  almost  exclusively  confined   to  Dammara  and  Araucaria, 
though  It  IS  a  noteworthy  fact  that  similar  structures  occur  rarely 


'i\ 


58 


ANATOMY  OF  THE  GYMNOSPERMS 


among  the  higher  Coniferales.  In  the  genus  Abies  they  are  prom- 
inent features  in  both  A.  Fraseri  and  A.  grandis.  In  the  former 
a  transverse  section  shows  them  to  be  prominent  and  scattering 
through  the  summer  wood,  more  rarely  in  the  spring  wood ;  while 
in  the  radial  section  the  resin  is  seen  to  be  massive  in  the  sum- 
mer wood,  forming  a  peripheral  layer  in  the  spring  wood.  In 
A.  grandis  the  resin  is  usually  more  abundant,  but  otherwise  the 
features  are  the  same. 

The  taxonomic  value  of  the  resinous  tracheids  applies  exclu- 
sively to  the  Cordaitales,  where  they  are  of  ordinal  value,  though 
in  Dammara  and  Araucaria  they  may  also  become  of  specific 
value.  In  Abies  they  are  so  sporadic  and  present  so  little  con- 
stancy as  to  be  of  no  value. 

From  a  phylogenetic  point  of  view  it  is  possible  to  determine 
the  position  which  they  occupy  in  the  general  scale  of  develop- 
ment, and  so  to  utilize  them  in  determining  the  position  of  plants 
in  which  they  may  occur.  That  they  are  met  with  in  their  most 
characteristic  form  almost  exclusively  in  one  of  the  most  ancient, 
as  also  in  one  of  the  relatively  primitive,  groups  of  Gymnosperms 
points  with  force  to  the  idea  of  their  being  also  a  primitive  form 
of  the  secretory  reservoir.  This  view  is  greatly  strengthened  by 
the  fact  that  in  such  plants  there  are  no  special  secretory  reser- 
voirs such  as  may  be  met  with  in  the  higher  Coniferae,  nor  do 
we  even  find  specialized  wood-parenchyma  cells  devoted  to  such 
purpose.  In  this  sense  the  sequence  of  the  resin-producing  struc- 
tures would  be  (i)  resinous  tracheids,  (2)  resin  cells,  (3)  resin 
cysts,  (4)  resin  passages.  The  relation  of  such  a  sequence  to  the 
general  phylogeny  would  be  that,  since  resinous  tracheids  appear 
in  a  sporadic  form  in  Abies  and  thereby  represent  a  limited  sur- 
vival of  a  primitive  character,  the  Coniferales  have  a  common 
origin  with  the  Cordaitales,  which,  developing  as  a  lateral  member 
of  the  main  phylum,  has  retained  this  feature  as  an  essential 
characteristic  while  it  has  disappeared  almost  completely  from  the 
main  line  of  descent.  Such  obliteration  is  fully  expressed  in  the 
Gingkoales,  which  have  also  been  developed  as  an  offshoot  from 
the  parent  stem. 


CHAPTER  IV 

BORDERED  PITS 

In  a  preceding  chapter  it  has  been  shown  how  the  bordered 
pit  originates  in  the  spiral  structure  of  the  protoxylem  through 
a  more  general  and  continuous  development  of  the  secondary 
layer  of  the  cell  wall.  We  are  now  concerned  with  an  inquiry 
into  the  detailed  structure  of  these  markings,  their  variations 
under  different  conditions  of  growth  and  situation,  and  their 
relations  to  taxonomy  as  well  as  to  phylogeny. 

It  has  been  seen  that  in  the  genesis  of  the  bordered  pit  the 
bands  of  adjacent  spirals  or  the  bars  of  a  scalariform  structure 
generally  enlarge  toward  one  another  so  that  the  intervening 
area  contracts  about  a  common  center,  but  the  edges  never  com- 
pletely meet,  so  that  a  pit  is  left  at  the  central  point.    In  such 
contraction,  however,  the  secondary  wall  is  not  joined  to  the  pri- 
mary, but  is  free  and  springs  from  it  as  an  arch  which  has  a 
circular  outline  and  a  central  orifice  (fig.  8).    As  such  pits  are 
always  paired  on  opposite  sides  of  the  primary  wall,  the  entire 
structure,  when  seen  in  tangential  section,  is  lenticular  in  form 
(fig.  II),  with  a  membrane  traversing  the  central  plane  and  two 
openings  opposite  to  one  another  at  the  extremities  of  the  minor 
axis.    From  this  it  is  obvious  that  the  pit  as  usually  seen  is  a 
double  structure  which  does  not  at  first  present  a  direct  opening 
from  one  tracheid  cavity  to  the  other,  for  so  long  as  the  tracheids 
are  growing  or  the  protoplasm  is  present  communication  between 
adjacent  tracheids  is  cut  off  by  the  primary  wall,  which  consti- 
tutes a  closing  or  ///  membrane.    By  a  subsequent  change  in  this 
latter  it  may  eventually  become  displaced  from  its  central  posi- 
tion and  then  lie  against  one  of  the  arches.    Under  such  circum- 
stances it  is  often  not  readily  discernible,  and  the  pit  apnears  as 
if  the  primary  wall  had  been  obliterated  within  its  limits.    In  the 

59 


6o 


ANATOMY  OF  THE  GYMNOSPERMS 


last  instance,  when  the  active  protoplasm  is  withdrawn  and  the 
cell  passes  into  a  permanent  condition,  the  membrane  disappears, 
and  the  pit  then  forms  a  lenticular  cavity  in  the  line  of  the  cell 
•.vail,  which  opens  into  adjacent  tracheids.    This  is  the  appearance 
presented  by  all  fully  developed  wood  of  the  Coniferje.    The 
obvious  purpose  of  such  pits  is  to  provide  channels  of  communi- 
cation between  adjacent  tracheids  which  would  otherwise  be  com- 
pletely isolated  by  the  impervious  nature  of  the  secondary  wall. 
This  fact  serves  to  explain  the  situation  in  which  such  pits  occur. 
Radial  walls.    The  characteristic  situation  of  the  bordered 
pits  is  on  the  radial  walls,  where,  as  was  shown  many  years  since 
(13,  i6o),  "  the  pits  of  contiguous  tracheids  always  correspond  to 
one  another  in  such  a  way  that  on  each  limiting  surface  all  the 
cavities  of  the  pits  of  one  fit  exactly  over  those  of  the  other. 
The  plano-convex  cavities  are  thus  applied  to  one  another  in  pairs 
so  as  to  form  the  lens-shaped  pit  cavities,"  as  seen  in  tangential 
section.    But  on  surfaces  abutting  on  elements  of  another  order, 
e.g.  parenchyma  cells,  the  bordered  pits  of  the  tracheids  corre- 
spond to  nonbordered  pits  or  else  are  opposite  an  unpitted  wall. 
Four  typical  variations  of  the  bordered  pits  may  be  recognized, 
—  (i)  the  multiseriate,  when  they  are  disposed  in  any  number 
of  rows  more  than  two,  (2)  the  two-seriate,  (3)  the  one-seriate 
with  occasional  pairs  of  pits,  and  (4)  the  strictly  one-seriate.    The 
general  sequence  thus  presented  will  be  found  to  be  in  direct 
accord   with   the  evolution  of  higher  types   of  structure  and 
organization. 

The  most  primitive  type  of  Gymnosperm  presenting  a  multi- 
seriate  arrangement  is  the  genus  Cordaites.  Among  eleven 
species  of  this  genus  which  have  been  critically  studied  within 
recent  years  (45)  there  is  a  general  agreement  in  the  constancy 
of  this  character  which  thereby  becomes  of  generic  Vf.!i)e.  In 
all  the  species  the  pits  are  disposed  in  such  a  compact  manner 
throughout  the  entire  extent  of  the  tracheid  as  to  present  a 
hexagonal  outline.  In  Cordaites  acadianum  they  are  two-  to  five- 
seriate  (plate  7).  In  other  species  they  vary  from  two-seriate 
in  C.  hamiltonense  and  C.  Newl  uxyi  (plate  8)  to  occasionally 


BORDERED  PITS 


6i 


four-seriate  in  C.  Clarkei.  In  the  majority  of  species  the  rows  are 
not  constant,  but  show  a  varying  number  from  one  to  three  or 
two  to  five,  this  variation  being  exhibited  by  adjacent  tracheids 
m  accordance  with  the  variation  of  the  latter  in  radial  diameter- 
and  viewmg  this  distribution  as  a  whole,  it  cannot  be  doubted 
that  It  represents  corresponding  differences  in  development.  One 
of  the  most  striking  features  of  the  genus  is  to  be  met  with  in 
C  Newberryi  (plate  8),  which  is  unique  in  the  segregation  of 
the  pits  into  groups  of  six  to  thirteen. 

In  Araucarioxylon  (28.  614).  while  conforming  to  the  char- 
acteristic form  and  compact  arrangement  presented  in  Cordaites 
the  pits  exhibit  far  less  constancy  in  their  serial  arrangement,' 
and  in  this  respect  they  are  at  once  comparable  with  those  of  the 
existing  Araucarias.  Among  the  latter  A.  Cunninghamii  shows  a 
one-  to  three-seriate  disposition,  A.  excelsa  is  one-  to  two-seriate 
while  A.  Bidwillii  is  strictly  one  seriate.  All  of  the  extinct  species 
as  comprised  m  the  genus  Araucarioxylon  not  only  show  similar 
variations,  but  such  variations  are  found  to  cover  a  much  wider 
range.    A  comparison  of  all  the  species,  both  recent  and  extinct 
now  available  for  that  purpose  is  of  interest  in  this  connection' 


i-Seriate 

X 
X 
X 

X 

2-Seriate 

S-Sekiate 

4-.SEKIATE 

A.  Bidwillii "... 

X 
X 
X 
X 
X 
X 

1 

X 

— . — 

wurtembergianum 

Schmidianum    .     .     . 

hugelianum 

excelsa  i  .     . 

arizonicum    .     .     . 

Edvardianum    .     .     . 

virginianum 

Doeringii      .    . 

subtile      .     . 

argilliacola   .... 

Heerii .... 

Cunninghamii' 

'.obertianum     .     . 



i 

X 

*  Kxistii 

ig  species. 

II 


63 


ANATOMY  OF  THE  GYMNOSPERMS 


Such  a  comparison  brings  into  strong  relief  the  fact  that  the 
Araucarias,  both  past  and  present,  constitute  a  transitional  group 
with  a  somewhat  wide  range  of  variations,  and  in  this  respect 
they  may  be  said  to  stand  between  the  more  stable  Cordaites 
and  Dammara  on  the  one  hand,  and  the  far  more  variable  Coni- 
ferae  on  the  other,  since  in  Dammara  australis  we  find  essentially 
the  same  features  of  structure  and  distribution  as  in  Cordaites, 
the  pits  being  one-  to  three-seriate.  The  sequence  presented 
above  may  be  held  to  be  in  the  inverse  order  of  development, 
and  A.  Robertianum  must  therefore  be  held  to  represent  the 
most  primitive  form. 

It  is  apparent  that  in  Cordaites,  Araucaria  (including  Arauca- 
rioxylon),  and  Dammara  the  pits  are  invariably  distinguished  by 
two  constant  features, —  ( i )  their  hexagonal  form,  and  (2)  their 
very  compact  disposition  throughout  the  entire  extent  of  the 
tracheid.    They  often  deviate  from  the  multi-^eriate  arrangement 
typical  of  the  group  as  a  whole  in  that  in  individual  cases  they 
are  reduced  to  a  one-seriate  arrangement.    They  thus  tend  to 
overlap  the  next  group,  which  is  distinguished  by  a  two-seriate 
disposition,  but  any  confusion  which  might  arise  from  this  cause 
may  be  overcome  by  reference  to  the  special  form  and  disposi- 
tion of  the  pits,  as  will  more  fully  appear  in  the  following  lines. 
Among  the  remaining  Coniferales  twenty  species  of  various 
genera,  or  17.2  per  cent  in  all,  show  a  two-seriate  arrangement,  and 
to  this  group  we  must  also  add  the  Gingkoales  and  various  fossil 
species.    Here  the  multiseriate  disposition  of  the  pits  involves 
features  which  at  once  distinguish  the  group  as  a  whole  from  the 
preceding,  clearly  placing  it  upon  a  higher  plane  of  development. 
The  pits  are  never  hexagonal  but  are  generally  elliptical  or  round, 
while  they  also  show  a  strong  tendency  to  extreme  segregation. 
When  brought  into  a  compact  arrangement,  as  in  Cupressoxylon, 
Sequoia,  or  various  species  of  Pinus,  they  are  flattened  only  along 
the  lines  of  limited  contact,  which  are  usually  confined  to  one 
end  of  the  pit  (fig.  8).   A  very  characteristic  feature  of  this  group  is 
the  further  fact  that  the  two-seriate  arrangement  is  not  constant, 
either  in  tl  0  same  section  or  in  the  same  tracheid.    Both  Pinus 


BURUERtU  FI'IS 


63 


taeda  and  P.  cubeniis,  as  also  Larix  americana  and  ''suga  cana- 
densis, afford  illustrations  that,  while  typically  two-seriate,  a  given 
section  may  show  a  strictly  one-seriate  arrangement,  and  this 
difference  also  obtains  as  between  contiguous  cells.  In  all  such 
cases  examination  will  show  that  the  variation  is  directly  related 
to  the  relative  size  of  the  tracheids  in  such  a  way  that  the 
narrower  tracheids,  or  those  arising  from 
a  less  vigorous  growth,  are  one-seriate. 
Within  the  individual  trachcid  thert;  is 


(SB 


^ 


CD 


FiG.g.     PiNUS    STROBUS. 

Kadial  section  showing  the 
form  and  disposition  of  the 
bordered  pit.s.     x  280 


F10.8.  PiNus  CUBENSIS.  Radial  section  showing 
the  form  and  disposition  of  the  bordered  pits. 
X  280 

a  strong  tendency  to  a  one-seriate  arrangement  in  the  central 
region,  while  it  is  two-seriate  at  the  extremities ;  and  this  law 
holds  so  true  that  in  those  species  which  are  exceptionally  two- 
seriate  judgment  should  be  reserved  until  it  is  seen  that  the 
one-seriate  form  holds  throughout. 

The  antithesis  of  the  multiseriate  type  is  found  in  the  one- 
.scriate  form.  This  is  typical  of  50  per  cent  of  all  the  species 
included  in  the  present  studies.  In  such  cases  the  form  of  the 
pit  is  never  hexagonal  or  specially  flattened.  When  the  disposi- 
tion  is  somewhat  compact,  as  in  Pinus  strobus  (fig.  9),  the  outline 


ii 


■  p¥  = 


44  ANATOMY  OF  THE  GYMNOSPERMS 

becomes  more  or  less  strongly  elliptical,  but  as  the  segregation- 
is  more  pronounced  a  definitely  circular  form  prevails  (fig.  10). 
Within  the  limits  of  the  individual  trucheid  the  same  law  of  dis- 
tribution obt«  IS  as  in  the  two-seriate  type,  whereby  segregation 
is  always  most  pronounced  in  the  central  region. 

Between  species  of  the  strictly  one-seriate  and  those  of  the 
strictly  two-scriate  type  there  is  an  intermediate  or  transition 
group  comprising  thirty-four  species,  or  29.3  per  cent  of  the  in 
vestigated  species,  into  which  members  of  the  other  two  groups 
may  occasionally  be  projected.    The  distin- 
guishing  feature  of  this  group  is  the  occur- 
rence of  pits  in  pairs,  which  are  usually 
distant  and  in  no  case  so  numerous  as  to 
distinguish  a  two-seriate  disposition.    They 
give  undoubted  proof  of  the  passage  from  one 
type  to  the  other.  Like  the  two-seriate  type, 
this  feature  is  not  confined  to  any  one  genus 
or  to  any  particular  group  of  genera,  but  it 
applies  with  equal  force  to  any  genus,  the 
members  of  which  may  therefore  represent 
any  or  all  of  the  three  types  here  specified. 
Viewing  the  distribution  of  the  bordered 
^'bu's°  Radia?seJr„    P'^'  from  the  Standpoint  of  zonal  devel- 
showing  the  bordered    opmcnt,  it  is  found  to  be  Universally  true 

strongest  tendency  to  a  mult '"seriate  arrange- 
ment. With  a  radial  increase  of  the  xylem  this  tendency  con- 
stantly diminishes,  with  the  general  result  that  the  pits  becoi..o 
more  strictly  one-seriate  and  more  distant  toward  the  summer 
wood  in  which  they  are  sometimes  wholly  obliterated,  this  being 
the  case  when  the  cell  wall  acquires  unusual  thickness. 

Upon  careful  examination  the  foregoing  facts  will  be  found 
to  be  in  exact  accord  with  the  law  formulated  by  De  Bary  with 
reference  to  variations  in  the  structure  of  spiral  tracheids  and 
the  genesis  of  bordered  pits,  as  already  stated.  In  accordance 
with  this  law  it  is  possible  to  conclude  that  relatively  rapid 


BORDERED  PITS 


t»s 


growth  IS  coordinated  with  a  primitive  development,  while  he 
converse  is  true  of  a  slow  rate  of  growth  which  i^  again  con- 
vertible into  terms  of  maturity.  On  th«  basis  we  may  pr. 
sent  the  following  general  outline  of  sequence  in  development, 
as  prehmmary  to  further  and  more  dctailcti  discusHion  of 
phylogeny : 

a-S  Mriate,  hexagonal  pits 

1-4  seriate,  hetagunal  pit* 

'-3  •"■iate,  hexagonal  pits 

1-3  seriate,  hexagonal  pim 

'-2  seriate,  round  or  oval  pits 
Higher  Coniferales,  1-2  seriate,  round  or  oval  pits 
Higher  Coniferales,  i-seriate  and  pairs,  round  or  oval  pits 
Higher  Coniferales,  i-seriate,  round  or  oval  pits 


Cordaitcs  .     . 
Araucarinxylon 
Araucaria 
Dammara.     . 
Giagko 


Compai^   throughi  ui   ii,r 
irai  lieid. 


Mi>re  or  1  (■■.«, 
■   often  stronjif!, , 
segrcirated. 


Tangential  walls.    The  occurrence  of  bordered  /  ',  in  the 
tangential  walls  is  a  well-known  and  characteristic   feature     f 
the  Conifers:.    In  the  case  of  fossil  forms,  to  which  Araucai- 
oxylon  offers  a  partial  exception,  they  cannot  be  satisfact(,rilv 
demonstrated  because  of  the  peculiar  altera- 
tions of  the  cell  wall,  but  that  they  are  pres- 
ent we  are  permitted  to  in*  r  from  analogy 
with  existing  species  upon  which  dependence 
must  be  placed  for  an  eluv  idation  of  the  gen- 
eral law.    The  typical  posit i<  a  for  such  pits 
is  upon  the  tangential  walls  of  the  summer 
wood,  where  they  arc  seen  most  satisfactorily 
in  radial  section,  inasmuch  as  they  are  always  ,  .  ..^ 

readily  observable  when  present,  and  their  v^,•..^^7^^^  ,,, 
most  essential  features  are  displayed  in  a  gantea.  Radial  sec 
manner  not  possible  in  a  tangential  section     *'°"  ^howinij  bordered 

(fia    ii\  pits  in  the  tangential 

^   *■    ,    '■  walls  of  the  summer 

This  position  obviously  results  because  of      **"°^-    ^  ^^ 
limitation  of  the  radial  walls  throi-h  radial  compression.    The 
pits  are  therefore  always  confine!  to  the  few  outermost  tracheids 
of  the  last-formed  summer  wood,  -nd  .n  some  cases  they  are  con- 
fined exclusively  to  the  last  tracheifi. 


fe-t 


p 

m 

i  ■  ' 

i 

66 


ANATOMY  OF  THE  GYMNOSPERMS 


Pits  occur  in  this  position  in  '/ij  per  cent  of  all  the  investi- 
gated species,  and  their  absence  in  28.3  per  cent  points  to  some 
special  features  in  development  which  may  be  assumed  to  have 
a  general  bearing  upon  the  questions  of  descent  and  relationship. 
In  Dammara,  as  represented  by  the  one  species  D.  australis,  such 
pits  are  a  prominent  and  characteristic  feature,  but  in  the  nearly 
related  Araucaria  they  are  remarkable  for  their  uniform  absence. 
In  the  primitive  Gingkoales  they  are  also  present,  but  among  the 
Taxaceas,  while  generally  present,  they  are  occasionally  wanting, 
as  in  Torreya  taxifolia  and  T.  nucifera,  or  in  06.6  per  cent  of 
the  investigated  species  of  that  genus.    Nowhere  else  among  the 
Coniferales  do  we  find  such  a  leature  until  we  reach  the  genus 
Pinus,  the  second  and  higher  section  of  which  is  almost  invariably 
characterized  by  their  absence,  thus  presenting  an  exceptional 
feature  to  the  extent  of  68.3  per  cent  of  that  genus.    That  such 
absence  represents  a  process  of  obliteration  conformable  to  De 
Bary's  law  cannot  be  doubted,  while  the  sporadic  recurrence  of 
this  feature  in  often  widely  separated  genera,  or  in  particular  spe- 
cies of  a  given  genus,  must  be  held  to  have  a  more  or  less  direct 
bearing  upon  the  general  course  of  development.    This  is  empha- 
sized by  the  observation  that  in  Larix  americana  and  L.  lepto- 
lepis,  as  also  in  Picea  bicolor,  there  is  a  more  or  less  pronounced 
tendency  to  an  obliteration  which  is  never  fully  developed.    This 
is  expressed  in  the  somewhat  remote  position  of  the  pits  and 
their  very  small  size,  which  renders  them  obscure  and  often  diffi- 
cult to  discover.    In  this  respect  these  species  represent  transi- 
tional forms. 

As  an  exceptional  feature  bordered  pits  may  sometimes  be 
found  upon  the  tangential  walls  of  the  spring  wood.  This  is  espe- 
cially noticeable  at  the  ends,  of  tracheids,  and  in  rare  cases  it 
may  apply  to  the  entire  extent  of  the  wall.  The  most  notable 
instance  of  this  kind,  because  practically  unique,  is  to  be  met 
with  in  Sequoia  gigantca  (figs.  1 2  and  1 3).  Those  spring  tracheids 
which  lie  in  direct  contact  with  the  summer  wood  of  the  pre- 
vious year  often  exhibit  this  feature  with  great  prominence,  but 
it  may  also  extend  radially  through  several  successive  tracheids. 


BORDERED  PITS 


67 


© 


© 


This  IS  undoubtedly  a  primitive  character,  and  in  the  one  case 

cited  It  possesses  some  value  for  the  purpose  of  specific  differ- 
entiation, but  in  general  terms  the  occurrence  of  bordered  pits 

in  such  positions  is  of  so  sporadic  a  nature 

as  to  give  this  feature  no  well-defined  value, 

either  for  taxonomic  or  phylogenetic  purposes! 

It  may,  nevertheless,  be  stated  with  respect 

to  the  pits  on  the  tangential  walls  of  the  tra- 

cheids  in  general,  that  in  their  distribution 

they  distinctly  conform  to  the  law  governing 

simi'.'r  structures  on  the  radial  walls. 

Reference  to  Cordaites  acadianum  shows 

that  in  the  multiseriate  pits  of  the  hexagonal 

form  these  structures  always   preserve  the 

spiral  arrange- 
ment character- 
ist  ic  of  the 
structures  from 

which  they  fig.  12.  sequou  gi- 
were  derived      "antfa.   Radial 
(plates   3-6), 
and  this  con- 
formity also  ex- 
tends to  the 

direction  of  the  spirals  which  gen- 
erally ascend  from  left  to  right. 
The  general  law  in  this  respect  has 
already  been  formulated  so  fully 

Fi<;.  13.   Sequoia  gioantea.    Tan-     ''^  ^^  ^^^V  (^^'  '^3)  as  to  make  it 

gentiai  section  showing  bordered    unnecessary  at  this  time  to  enter 

pits  in  the  taneential  walls  of  thp        _  -a.  .  . 

spring  wood.  «^  4'^' "'"'*  "f 'he    upon  ,ts  Consideration  more  in 

detail,  beyond  a  reference  to  one 
or  two  special  features  and  some  apparently  exceptional  ca.ses. 
U  hi  e  the  spiral  arrangement  is  always  typical  in  such  genera  as 
Cordaites,  Danimara,  Araucaria,  etc.,  it  is  not  obvious  in  those 
cases  where  the  pits  are  strictly  ore-seriate  and  often  remote 


section  showing  the 
bordered  pits  on 
the  tangential  walls 
,  of  the  .spring  wood. 
X  280 


© 


68 


ANATOMY  OF  THE  GYMNOSPERMS 


i    M 


from  one  another.  Nor  is  it  apparent  at  first  sight  in  those  cases 
of  two-seriate  pits  where,  as  in  Cupressoxylon  Dawsoni  from  the 
Cretaceous,  Larix  americana.  Sequoia,  and  various  species  of 
Pinus,  the  pits  are  always  paired  off  in  such  a  way  that  the  axis 
of  each  pair  is  at  right  angles  to  the  axis  of  the  cell  (fig.  8). 
Two  explanations  are  here  possible :  (i)  the  spirals  are  in  reality 
two-seriate,  and  are  projected  through  the  alternate  members  of 
the  two  rows  of  pits ;  or  (2)  the  disposition  of  the  pits  repre- 
I  sents  an  extreme  phase  in  the  flattening  of 

the  original  spirals  conformably  to  a  higher 
type  of  development.  This  view,  which  seems 
the  more  reasonable,  is  in  direct  harmony  with 
De  Bary's  law,  while  it  receives  additional 
support  from  the  form  and  direction  of  the 
pit  orifice. 

The  orifice  of  the  pit  is  variable,  at  differ- 
ent times  being  round,  when  the  pits  are  also 
round  and  more  or  less  distant ;  oval  or  oblong, 
when  the  pits  assume  corresponding  forms; 
or,  in  the  summer  wood,  lenticular  or  oblong. 
The  transversely  elliptical  pits  of  Pinus  stro- 
bus  (fig.  9),  the  orifice  of  which  is  also  trans- 
versely oblong,  as  also  the  similar  pits  of  Pinus 

""gens.  Torde'rTd  ''"''^"''^  ^^^^  ^^'  ^^^''^  Substantial  proof  in 
pits  on  the  radial  Confirmation  of  the  probable  correctness  of 
walls  of  the  sum-   this  view.    In  the  summer  wood  the  pit  orifice 

mer  wood,    x  280  ,  ... 

commonly  assumes  a  position  which  appears  to 
offer  a  direct  contradiction  to  this  conclusion.  In  Pinus  strobus 
(fig.  10)  the  orifice  is  oblong  and  parallel  with  the  tracheid  axis. 
In  Pinus  pungens,  as  in  many  others  of  the  same  genus  (fig.  14), 
the  narrow  orifice  is  extended  above  and  below  into  a  diagonal 
slit  of  great  length,  forming  a  narrow  angle  with  the  tracheid 
axis.  At  first  sight  this  would  seem  to  imply  that  these  features 
represent  primitive  spirals,  the  original  direction  of  which  has 
not  been  greatly  if  at  all  modified,  but  one  or  two  considerations 
will  assist  us  to  a  correct  interpretation  of  this  feature.    In  the 


BORDERED  PITS 


69 


I 


(2 


m 


Fig.  15.  CupREssus  noot- 
KATENsis.  Radial  section 
showing  deformed  bor- 
dered pits.    X  280 


o 


first  place,  it  is  to  be  observed  that  such  positions  and  modifications 
of  the  orifice  are  invariably  associated  with  the  summer  wood; 
if  they  occur  in  the  spring  wood,  it  is  the  result  of  maceration 
and  commonly  appears  in  fossil  plants  or  woods  in  process  of 
decay,  and  they  are  always  moi,t  conspicuous  in  those  tracheids 
which  have  experienced  the  most  profound  modifications  with 
respect  to  the  growth  in  thickness  of  the  secondary  walls.    It 
has  already  been  shown  in  the  case  of  Taxus  and  Torreya  that 
there  is  no  necessary  connection  between  the  spiral  bands  and 
the  spiral  lines  of  striation,  —  that,  as  a 
matter  of  fact,  as  particularly  illustrated 
by  Torreya  taxifolia,  the  two  arc  quite 
distinct   from   one   another   under   ordi- 
nary conditions  of  development ;  but  in 
cases  where  the  wall  experiences  extreme 
growth  in  thickn-^ss  the  obliteration   of 
the  original  spiral  structure  is  complete, 
and  at  the  same  time  it  is  replaced  by  the 
normal  striation  of  the  wall,  which  then 
becomes  most  pronounced.    Instances 
.such  as  those  afforded  by  Pinus  strobus 
and  P.  insignis  may,  according  to  this  in- 
terpretation, be  held  to  represent  the  final 
phases  in  the  obliteration  of  the  original 
spirals,  and  they  therefore  constitute  char- 
acters indicative  of  the  highest  type  of  de- 
velopment.   In  a  few  cases  the  structure 

of  the  bordered  pit  presents  exceptional  forms.  In  Cupressus 
nootkatensis  the  pit  orifice  shows  either  unusual  want  of  regu- 
larity in  outline  and  marked  eccentricity  of  position,  or  it  is  so 
enlarged  as  to  leave  only  a  narrow  border  to  the  round  or  oval 
pit  (fig.  15).  Similar  features  occur  occasionally  in  other  genera, 
and  they  are  generally  conspicuous  in  Pinus  tieda.  De  Bary  has 
directed  attention  to  the  same  feature  in  Ephedra  (13,  159) 
and  Pinus  sylvestris,  and  he  correctly  interprets  it  as  a  form 
of  arrested  development.    Alterations  also  arise  as  a  feature  of 


70 


ANATOMY  OF  THE  GYMNOSPERMS 


<0) 


secondary  growth  in  those  cases  in  which  the  wall  acquires 
unusual  thickness.    This  is  typically  the  case  in  Pinus  cubensis 
where  m  plan  (fig.  i6)  the  orifice  is  extended 

vertically  to  a  length  often 

twice  the  diameter  of  the 

original  pit.    In  tangential 

section,  according  to  the 

particular  direction  of  the 

plane  of  section  (fig.  17), 

the  orifice  is  either  of  uni- 
form width  or  it  enlarges 
BENsis.  Radial    Constantly  through  the  en- 
H7"°J!i,l*'?'"5    *'■■«  thickness  of  tho  later 

deformed  bordered 

pits.   X280  growth,  from  within  out- 

wards. That  such  unusual 
forms  are  features  of  extreme  secondary  growth  of  the  wall, 
and  that  they  may  be  anticipated  in  all  cases  where  such  modi- 
fications of  the  walls  occur,  is  a  reasonable  deduction  from  the 
observed  facts. 


(!) 


Fig.  16.  Pinus  cu- 


Fig.  17.  Pinus  CUBEN- 
SIS. Tangential  sec- 
tion of  bordered  pits 
as  in  fig.  16.    X  280 


Bordered  Pits  —  Taxonomic  and  Phvlogenetic 

For  taxonomic  purposes  the  bordered  pits  possess  a  definite 
though  often  limited  value.  In  the  genus  Cordaites,  as  also  in 
Araucarioxylon,  Araucaria,  and  Dammara,  this  is  expressed  in 
the  hexagonal  form  together  with  their  very  compact,  chiefly 
multisenate  arrangement  throughout  the  entire  extent  of  the 
tracheids,— characters  which  are  of  generic  value  and  at  once 
serve  to  separate  these  genera  from  all  others.  The  contrast- 
ing differential  feature  is  then  to  be  found  in  the  pits  of  the  oval 
or  round  form,  together  with  their  two-seriate  or  one-seriate  dis- 
position, with  a  more  or  less  marked  tendency  to  segregation 
rhis  IS  characteristic  of  the  Gingkoales  and  all  the  Coniferales, 
both  fossil  and  recent. 

As  a  differential  character  of  subgeneric  value,  the  occurrence 
of  bordered  pits  on  the  tangential  walls  of  the  summer  wood  of 


BORDERED  PUS 


71 


the  firs  section  of  Pinus  (the  soft  pines)  and  their  almost 
mvarmbe  absence  from  the  same  structural  region  in  the  second 
section  the  hard  pmes)  is  one  which  may  be  always  relied  upon 
For  the  purposes  of  specific  dif?crentiations  the  pits  onVhe 
tangential  walls  possess  a  distinctly  inferior  value,  which  must  be 
confirmed  m  most  cases  by  the  evidence  of  other  factors  Their 
utility  m  this  respect  is  made  sufficiently  clear  in  the  various 
cliagnoses  and  m  the  artificial  key.  without  further  discussion 
at  this  time. 

In  the  genus  Cordaites,  according  to  the  provisional  specific 
differentiations  of  fossil  forms  as  at  present  generally  empl^ed. 
the  number  of  rows  of  pits,  or  their  segregation  into  definite 
groups,  are  characters  of  well-defined  specific  value,  since  they 
are  among  the  few  features  which  maybe  utilized  with  certainty 
for  this  purpose.    Thus  C.  acadianum  with  its  two  to  five  rows 
C.  matenanum  with  two.  rarely  three  to  four,  rows,  C.  hamiU 
tonense  with  two  rows,  and  C.  Newberryi  with  two  rows,  in  groups 
o   SIX  to  thirteen  pits,  rest  upon  a  basis  which  is  not  only  easy 
of  recognition  but  which  may  be  applied  with  full  assurance 
In  Araucaria  the  three  species  investigated  may  be  similarly 
differentiated  from  one  another.    The  same  rule  is  applicable  to 
Torreya  taxifolia.  which  is  thereby  separable  from  the  other  spe- 
cies;  likewise  to  Cupressoxylon  Dawsoni.  Tsuga  canadensis,  aVd 
Larix  amencana.  and.   among  the  pines,  to   P.  Lambertiana, 
P.  clausa,  P.  Sabmiana,  P.  ta^da,  P.  palustris.  and  P.  cubensis. 
It  IS  to  be  observed,  however,  that  the  constancy  which  charac- 
terizes this  feature  in  Cordaites  and  Araucaria  is  wanting  in  the 
higher  Abietinea..    In  Larix  there  is  such  variation  that  very 
careful  scrutmy  is  required,  while  in  the  genus  Pinus  the  num 
ber  of  exceptions  to  the  typical  character  increases  greatly  and  is 
liable  to  cause  some  difficulty  in  the  final  determinations  unless 
much  care  ,s  exercised.   Pinus  treda  offers  a  conspicuous  illustra- 
lon  of  this  fact,  as  may  be  seen  by  reference  to  the  analytical 
key.    It  IS  therefore  manifest  that  the  value  of  the  bordered  pit 
tor  taxonomic  purposes  is  most  clearly  defined  in  the  lower  types 
of  the  Coniferales.  and  that  their  value  diminishes  steadily  with 


72 


ANATOMY  OF  THE  GYMNOSPERMS 


an  advance  towards  higher  forms  of  organization  and  develop- 
ment. In  all  cases  where  exceptional  forms  introduce  diagnostic 
difficulties  these  may  be  overcome  by  the  controlling  effect  of 
associated  characters. 

We  are  now  in  a  position  to  examine  the  data  at  hand  with  a 
view  to  determining  the  bearing  of  the  bordered  pits  upon  ques- 
tions of  phylogeny. 

Having  reference  to  the  origin  of  the  bordered  pit  and  the 
various  modifications  it  presents  in  the  course  of  development, 
it  cannot  be  doubted  that  the  hexagonal,  multiseriate  pits  of 
Cordaites,  Araucarioxylon,  Araucaria,  and  Dammara  place  these 
genera  in  a  relatively  inferior  position,  —  a  view  which  gains  a 
large  measure  of  support  from  the  well-known  and  extensively 
multiseriate  disposition  shown  in  Heterangium  Grievii  (81,  341), 
but  the  facts  so  far  discussed  have  not  as  yet  thrown  any  special 
light  upon  the  relative  positions  of  the  separate  genera. 

An  examination  of  twelve  species  of  Cordaites  shows  that  the 
bordered  pits  exhibit  a  much  wider  range  of  serial  variation  than 
any  other  genus  covered  by  the  present  studies.    If  then  we 
accept  the  general  principle  with  respect  to  the  development  of 
the  bordered  pits  as  already  illustrated,  it  cannot  be  doubted  that 
the  two-  to  five-seriate  pits  stand  much  nearer  to  the  primitive 
form  of  the  tracheid  than  do  the  one-seriate.    From  this  point 
of  view  it  is  then  evident  that  in  C.  recentium,  the  name  of  which 
is  thereby  seen  to  be  fully  justified,  the  one-seriate  pits  place  it 
at  the  upper  end  of  a  series  which  has  its  inferior  termination  in 
the  two-  to  five-seriate  C.  acadianum,  while  intermediate  forms 
appear  between  the  two  as  members  of  a  series  of  nine  variants, 
and  it  is  possible  to  arrange  these  in  such  a  manner  as  to  exhibit 
the  probable  sequence  in  development,  as  seen  by  table  on  the 
following  page. 

The  wide  range  of  variations  here  shown,  especially  when 
compared  with  other  genera,  ..t  once  serves  to  suggest  that 
Cordaites  was  in  this  respect  somewhat  of  the  nature  of  a  tran- 
sition group  from  which  others  were  given  off,  or  else  that  it 
epitomized  the  collective  changes  through  which  a  number  of 


BORDERED  PITS 


73 


genera  must  have  passed.  And  inasmuch  as  this  genus  ex 
hib.ts  a  more  highly  developed  multiseriate  arrangement  than 
any  other  within  the  general  phylum,  we  must  concede  that  it 
IS,  with  respect  to  this  character,  the  most  primitive  of  all. 

Serial  Variations  in  the  Borderei.  Fits  ok  Corimites 


C.  acadianum 
ohioense  .     .     . 
ouangondianum 
materiarium 
Clarkei     . 
annulatum 
Brandlingii 
materioide 
illinoLsense 
hamiltoneiiMe 
Newberryi 
recentium 

The  genus  Araucaria  shows  a  much  more  restricted  range  of 
variations,  there  being  only  four  variants  pretty  uniformly  dis- 
tributed among  fourteen  species,  both  recent  and  fossil  (a^tc 
p.  6 1).    While  the  most  highly  developed  members,  four  in  num' 
l)er  are  represented  by  one-seriate  pits,  the  most  primitive  form 
of  four-senate  pits  occurs  in  only  one  case, -A.  Robertianum 
It  ,s  therefore  manifest  that  this  genus  is  obviously  of  a  more 
n.lvanced  type  than  Cordaites,  from  which  it  undoubtedly  origi- 
nated.   Dammara  being  represented  by  only  one  s,>ecies,  it  ^s 
not  possible  to  locate  it  more  definitely  than  to  say  that  the  one- 
to  three-seriate  disposition  of  its  pits  would  place  it  in  a  posi- 
tion equivalent  to  that  occupied  by  Araucaria  Cunninghamii,  and 
therefore  about  three  fourths  of  the  way  down  the  scale  for  that 
senus.    This  fact  points  with  much  force  to  the  idea  that  of  the 
two  genera  Dammara  is  of  relatively  lower  type. 


H 


74 


ANATOMY  OF  THE  C.YMNOSPERMS 


The  Gingkoalcs  and  the  Conifcralcs  as  a  whole  exhibit  an 
obviously  higher  tyj)e  of  development  than  the  preceding  group, 
in  consequence  of  the  more  pronounced  tendency  to  segrega- 
tion of  the  pits,  which  are  now  either  elliptical  or  round,  and 
never  hexagonal.  This  distinction  is  so  clearly  defined  and  con- 
stant as  to  support  the  idea,  which  gains  force  in  other  ways, 
that  Cordaites,  Araucaria,  and  Dammara  are  clearly  related 
members  of  a  principal  branch  of  the  original  stock,  and  that 
they  therefore  diverge  considerably  from  the  particular  line 
of  descent  within  which  we  find  both  the  Gingkoales  and  the 
Coniferales. 

Gingko,  being  the  unique  representative  of  an  ancient  line, 
cannot  very  well  be  brought  into  the  present  discussion  very 
much  in  detail.  On  other  grounds  it  is  known  to  be  a  primitive 
form  representing  a  group  distinctly  inferior  to  the  Coniferales, 
and  this  view  is  supported  by  the  disposition  of  the  pits  in  two 
series,  a  character  which,  if  taken  alone,  weald  give  the  genus 
rank  with  Torreya  taxifolia  among  the  Taxaceae,  but  when  re- 
garded collectively  would  phce  the  genus  distinctly  below  the  Co- 
niferales as  a  whole.  This  evidence,  then,  indicates  that  the 
Gingkoales  must  have  arisen  as  a  side  line  at  some  point  inferior 
to  the  Coniferales  but  superior  to  the  Cordaitales. 

In  the  Taxacert  the  bordered  pits  do  not  in  themselves  afford 
very  conclusive  evidence  as  to  the  relative  position  of  the  family. 
Among  the  eight  investigated  species,  representative  of  three 
genera,  only  three,  and  chiefly  two,  variants  occur.  Taken  alone, 
the  disposition  of  the  pits  would  lead  to  no  final  conclusion,  but 
other  factors  permit  of  placing  this  family  in  the  inferior  posi- 
tion usually  assigned  to  it.  In  the  genu.s  three  variants  are 
found,  —  the  one-to-two  rows  of  T.  ta\if(»]ia,  the  one  row  or 
pairs  of  T.  californica,  and  tic  strictly  <>!.■  seriate  form  of  T. 
nucifera.  In  Taxus  only  two  variants  apj).  ar,  —  the  one  row 
or  pairs  of  T  floridana  and  the  one-soriate  disposition  as  found 
in  the  remaining  three  species.  The  one  representative  of  Podo- 
carpus  shows  but  one  variant,  and  that  is  one-seriate.  From 
this  it  is  obvious  that  tho  generic  sequence  must  be  in  the  order 


BORDEREP  PITS 


75 


given,  and  that  the  sequence  of  species  must  be  approximatclv 
as  g,vcn  in  the  table  of  anatomical  cbta  '  PP^^^'niatcIy 

The  observations  so  far  made  apply  altogether  to  the  pits  on 
he  radial  walls.    We  may  now  pass  to  a  considen^tion  If  their 
relation  to  the  tangential  walls,  a  factor  which  does  not  call  for 
very  extended  discussion.    This  feature  is  found   to  apply  to 
71.7  per  cent  of  all  investigated  species  exclusive  of  fossils 
It  .8  wantmg  m  three  species  of  Araucaria.  representing  2  58 
per  cent ;  m  two  species  of  Torreya.  or  ,  .72  per  cent ;  andin  the 
entire  second  section  of  Pi„us  to  the  extent  of  twenty-eight 
speces.  or  24..  per  cent.    But  the  occurrence  of  pits  on  fhe 
tangentul  walls,  in  common  with  those  on  the  radial  walls  i! 
a  we  l-known  feature  of  the  Sigillarias  («i.  .98).  where    he 
pnm.nve  character  is  well  established,  and  we  cTn  hardly  doub 
that  the.r  final  el.mmation  in  the  higher  pines  is  the  expres- 
s.on  of  a  final  phase  in  development  consistent  with  the  pos  tion 
usually  assigned  those  plants.  I^sinon 

The  absence  of  pits  from  the  tangential  walls   of  certain 

tZTT  7     "^""^'^  "  ^°  ^  '"^^^P-^^d  -  -«  of  those 
I.Td  '""''■'  '  ''''''''  'yP'  °^  development  which 

never  become  permanent  in  the  same  line,  but  which  are  to  be 
met  with  as  one  of  the  invariable  features  of  evolution 
The  remaming  genera  of  the  Conlferales  present  so  few  devia- 

Xon^tl^*^"'''!  '^'V"''  '^'y  ^^""°^  ^'  differentiated 
ful  y  on  the  basis  of  the  bordered  pits.  This  character  never- 
theless has  a  definite  value  in  association  with  others,  as  in  the 
genus  Sequoia  or  some  of  the  hard  pines.  Larix  americana.  etc 

he  general  sequence  of  genera  may  be  recognized  by  the  bor- 

le.ed  p.s  only  m  so  far  as  these  structures  serve  to  confirm 

and  emphasize  the  conclusions  reached  in  other  ways,  and  this 

elr 'hT'  T^^'T  ^'■°'"  '"  '"''P^^^'^"  °^  '^'  ^-ble  already 
referred  to.  It  will  nevertheless  serve  a  useful  purpose  at  the 
present  moment  to  ascertain  the  general  sequence  based  upon 

h  ;:;7'^"^^f  „d'«t"bution  of  the  principal  variants,  as  seen  by 
the  table  on  following  page. 

'  Appendix  A. 


'Ill 


76 


ANATOMY  OF  THE  ClYMNOSPERMS 


Comparison  op  the  PRiNriPAi.  Variations  in  tiii    Serial  Arranok- 
MEN!    -ir  Bordered  Pits,  hv  Pkrckntaoks 


TllTAl 

" 



— — . 

1 

Vakiatiuhi 

'i 

J-4 

*-j 

'J 

3 

1-1 

Paim 

1 

Cordaites   .    . 

9 

«3 

JSO 

i6.6 

25* 

■6.6 

33-3 

Uammara  .     . 

1 

6.6 

20.0 

400 

Araucana  .     . 
f'ingko  .    .    . 

4 

6.6 

20.0 

40.0 

lOO.C 

J3-3 

Sequoia      .    . 

1 

1 

lOO.O 

Larix     .    .     . 

3 

2 

I 

Taxodium  .    . 

3J3 

33  3      333 

Libocedrus 

25.0 

100.0 

75.0 

Thuya    .     .     . 

I 

100.0 

Pseudotfuga  . 
Pinus     .    .     . 

3 

3 
3 

2 

50.0 

50.0 

Abiet     .    .    . 

17.1 

4'  5 

41-4 

Taxui    .    .     . 

136 

*7-3 

59.1 

Tsuga    .    .     . 
Picea     .    .    . 

3 

2 

16.7 

25.0 
16.7 

75-0 
66.6 

Podocarpus 

1 

10.0      90.0 

1     .,^»» 

Thujopsia  .     , 
Cryptomeria  . 

I 
1 

100.0 
100.0 

With  respect  to  specific  differentiations  it  has  already  ap- 
peared that  the  bordered  pits  may  be  employed  with  success 
in  Taxus  and  Torreya.  In  Cupressus  this  rule  also  applies  to 
C.  pisifera  and  C.  macrocarpa,  both  of  which  are  distinguished 
by  having  their  pits  in  one  row  or  pairs,  while  the  remaining 
seven  species  have  strictly  one-seriate  pits.  An  instructive  ex- 
ample is  afforded  by  Cupressoxylon  Dawsoni.  In  this  species, 
which  is  of  early  T'^rtiary  age  (Lignite  Tertiary),  the  pits  are 
typically  two-seriate,  being  disposed  in  a  very  compact  manner 
similar  to  that  found  in  existing  Sequoias.  But  in  a  series  of 
eleven  specimens  it  is  clearly  seen  that  two  variants  are  repre- 
sented, the  second  being  a  one-seriate  form.  These  variations 
are  also  found,  as  in  the  other  Coniferales,  to  be  directly  related 
to  variations  in  the  size  and  rate  of  growth  of  the  tracheid.  It 
cannot  be  doubted,  then,  that  C.  Dawsoni  is  a  more  primitive 


BORDERED  PITS 

77 

reprcientative  than  any  species  now  existing,  and  that  it  is  sub- 
.tant.,.y  the  ancestral  form  of  the  genus,  so  far  as  we  know 

In  I^ru  the  four  investigated  species  may  be  differentiated 
pretty  fully,  and  this  rule  applies  w^th  particular  force  ^f 
amrncana  and  L.  occidentalis.  both  of  which  are  distinguished' 
by  t w<>-senate  forms.  Among  the  pines  P.  Lambertiana,  P  clau« 
'.  Sabm..^  P.  t«da.  P.  palustris.  and  P  cubensis  arc  reaS"; 
d  ffercntuted  from  the  others  by  the  two-seriate  pits.  In  U 
other  cases  than  those  specifically  indicated  the  bordered  pits 
afford  an  madeqimte  basis  for  specific  differentiation.  ^ 

It  >s  now  apparent  that  segregated  round  or  oval  pits  in  one 

ZtTn  th    r     ",  ^'/'^P'^-"^-^  '^^  highest  type  o'f  develop 
ment  m  the  Comferales.  and  any  deviation  from  this  must  L 
taken  to  mdicate  the   survival  of  more  primitive  conditions. 
po,n  mg  to  derivation  from  a  type  like  that  of  Araucarilo 
Corcaucs.    Prom  this  point  of  view  the  occurrence  of  pits  in 
oncto-two  rows  in  Larix  americana.  Torreya  taxifolia.  Sequoia. 
Tsuga  canadensis,  and  various  species  of  Pinus  indicates  the 
survival  of  ancestral  characters  which  are  partial  to  the  extent 
of  7.2  per  cent,  and  complete  to  the  extent  of  10.8  per  cent 
That  such  deviations  from  the  usual  type  of  structure  are  either 
survivals  or  reversions  which  serve  to  indicate  a  common  origin 
cannot  be  doubted,  more  especially  as  they  do  not  occur  at  a 
fixed  point  near  the  original  type,  but  they  arise  sporadically 
n  widely  separated  genera.    The  tendency  of  such  evidence, 
hen  IS  to  show  a  common  ancestry  for  the  various  genera  of 
the  Taxaceae  and  Conifers,  a  view  which  is  greatly  strength- 
ened by  the  testimony  afforded  by  the  spiral  tracheids  of  Larix 
americana.  Pseudotsuga.  and  Pinus  tada. 


MHCROCOrV   RBOIUTION   TiST  CHART 

(ANSI  and  ISO  TEST  CHART  No.  2) 


1.0 


1.1 


Li  123 

|23 

■  2.0 

kbu 

U£ 

lu 

III  ^-^ 

lll^^s 

^  /APPLIED  IIVHGE    Inc 

^^-  1653  East   Main   Street 

r-S  Roctiester.  New  York        1*609       USA 

Jgg  (716)   482  -  0300  -  Phone 

ass  (716)   2SS  -  5989  -  Fax 


Ij 


CHAPTER  V 


MEDULLARY  RAYS 


General  Structure 

The  medullary  ray,  in  the  various  details  of  its  structure, 
as  presented  radially  and  tangentially,  comprises  some  of  the 
most  important  features  for  diagnostic  and  taxonomic  pur- 
poses. While  it  presents  numerous  variations,  these  are,  in  the 
main,  of  such  a  nature  as  to  give  them  very  positive  value  for 
both  generic  and  specific  differentiations.  Primarily  the  medul- 
lary rays  are  to  be  regarded  as  a  residue  of  the  original  funda- 
mental structure,  which  has  been  left  over  in  the  genesis  of  the 
primary  stele,  but  they  are  capable  of  reproduction  or  extension 
under  the  influence  of  the  cambium  in  the  course  of  secondary 
growth.  In  all  such  cases,  however,  they  are  typically  composed 
of  the  same  elements  which  are  necessarily  parenchymatous. 
Deviations  from  this  structure  may  appear  through  the  intro- 
duction of  other  elements,  but  such  alterations  always  arise  in  a 
manner  which  indicates  their  relation  to  the  evolution  of  higher 
types  of  organization. 

In  a  transverse  section  the  medullary  ray  appears  usually  as 
a  si"iple,  radial  series  of  elongated  cells  with  transverse  termi- 
nations. Deviations  from  this  type  of  structure  occur  only  in 
the  case  of  the  rather  rare  two-seriate  forms,  which  appear  in 
the  transverse  plane  of  section  only  at  wide  intervals,  or  in  the 
case  of  rays  which  contain  resin  passages,  as  in  Picea,  Pinus, 
Larix,  etc.,  when  the  structure  presents  a  varying  aspect  depend- 
ent upon  the  particular  plane  of  section.  In  Pinus  reflexa  the 
side  walls  of  the  ray  cells  may  be  seen  projecting  into  the 
cavities  of  adjacent  tracheids,  where  they  form  short,  saclike 
bodies   of  the  general  nature  of  thyloses,  which  they  really 

78 


MEDULLARY  RAYS  yg 

are  (fig.  i8).  Such  a  feature  is  of  specific  value  in  differentia- 
tion. With  this  exception  the  ray  presents  no  features  in  this 
plane  of  section  which  merit  special  consideration 

Radia/ section.   Viewed  radially,  the  medullary  ray  is  seen  to 
be  composed  of  a  series  of  cells  e.xtended  in  a  radial  direction  and 
superimposed  so  as  to  form  a  muriform  band  from  one  to  many 
cells  in  height.    In  general  terms,  the  higher  the  ray  the  lower 
the  component  elements,  from  which  it  follows  that  in  one-celled 
rays  the  cells  are  usually  highest ;  but  this 
feature  is  only  of  general  interest,  since 
it  rarely  has  a  bearing  upon  the  chief  ques- 
tions at  issue.    In  some  cases  two  struc- 
tural types  may  be  recognized,  —  the  one 
containing  resin  passages,  the  other  devoid 
of  such  structures.    Where  such  passages 
occur  the  structure  of  the  ray  shows  a 
variation  of  detail  which  makes  it  of  no 
value  for  diagnostic  purposes,  and  the  rela- 
tion is  one  which  possesses  interest  only 
in  so  far  as  it  applie,-  to  the  distribution  of 
the  resin  passages  themselves. 

A  feature  of  primary  importance  in  the 
constitution  of  the  ray  is  the  occurrence 

of  two  kinds  of  parenchyma  cells.    In  95    Fig.  18.  p.nus  keklexa. 
per  cent  of  the  genera  the  upper  and  lower      Transverse  .section  of 
walls  are  always  thickened  by  secondary       ^  '"'''"""^  "^  '^°" 
growth  and  more  or  less  strongly  perfo- 
rated by  simple  pits  (figs.  19  d,  25,  and  2;). 
This  feature  also  applies  to  56.1  per  cent  of  the  genus  Pinus 
It  possesses  no  special  value  for  either  sj^ecific  or  generic  differ- 
entiations except  so  far  as  it  .^plies  to  cells  which  are  markedly 
different  and  justify  the  special  terms  fhcl-  walkcUnA  thin  zvalled. 
It  is  obvious,  then,  that  the  thick-walled  cell  is  to  be  regarded  as 
the  normal  structure  for  the  ray  of  the  Coniferales  as  a  whole, 
while  the  thin-walled  represents  the  exceptional  form  which  is 
introduced  in  response  to  some  special  demands.   Although  the 


ing  the  inflation  of  the 
cells  opposite  tracheid.s. 
X  300 


8o 


ANATOMY  OF  THE  GYMNOSPERMS 


thick-walled  cells  occur  in  the  genus  Pinus  to  the  extent  of  56  per 
cent,  they  show  a  diminishing  frequency,  eventually  becoming  rare 
and  are  ultimately  replaced  by  thin-walled  cells.  Reference  to 
them  in  the  following  diagnoses  is  always  specified  by  ( i).  In  43.9 
per  cent  of  the  genus  the  upper  and  lower  walls  are  thin  and 
absolutely  devoid  of  pits.  For  diagnostic  purposes  such  cells  are 
always  referred  to  as  (2).  In  some  cases  they  are  so  undeveloped 
as  to  be  obscure  and  readily  broken  out  in  the  process  of  section 


Fig.  19.  Pinus  palustris.  Radial  section  of  a  medullary  ray  showing  charac- 
teristic pits  on  the  lateral  walls :  a,  a  thin  wall  broken  out ;  b,  thick-walled 
parenchyma;  <-,  thin-walled  parenchyma,    x  280 

cutting,  so  that  they  are  often  entirely  wanting  (fig.  19,  a-<). 
Such  thin-walled  cells  are  typically  developed  m  P.  palustris, 
P.  taeda,  etc.,  and  it  is  to  be  observed  that  they  are  always  asso- 
ciated with  the  highest  forms  of  development.  Transition  forms 
occur.  These  are  first  seen  in  the  soft  pines,  where  occasional 
thin-walled  cells  devoid  of  pits  are  interspersed  and  are  often 
conterminous  with  the  thick-walled  elements.  In  the  ha*-  dnes 
the  same  relation  e.\ists,  but  it  is  gradually  reversed  u.    a  the 


MEDULLARY  RAYS 


8i 


thin-walled  cells  altogether  predominate.    Such  gradations  are 
exhibited  in  P.  Coulteri,  P.  Jeffreyi,  P.  pungens,  P.  tieda.  P  cu- 
bensis.  and  P.  inops,  and  they  afford  valuable  evidence  as  to 
the  sequence  in  development  of  the  species.    In  P   Murrayana 
P.  cubensis.  and  P.  insignis  the  transition  forms  e.xhibit  much 
more  detailed  gradations,   by  virtue  of  which  it  is  often  ex 
ceedmgly  difficult  to  Jistinguish  between  the  two  forms  of  cell 
since  whether  conterminous  or  parallel  the  variations  in  thickness 


"^""tion  IfTflT  "'^j-CHUM.    Medullary  ray  showing  the  structure  and  posi- 
t  on  of  the  p  ts  on  the  lateral  walls;  the  straight  ray  cells  and  the  thin 
straight,  terminal  walls,     x  280  ^  j-  i.c.is  ana  ine  tnin, 

change  in  such  a  way  that  the  one  type  passes  gradually  into 
the  other.  When  these  variations  are  viewed  collectively  and 
taken  together  with  the  general  fact  that  the  thin-walled  cells 
are  a  feature  of  the  higher  types  of  organization,  we  may  reason- 
ably conclude  that  the  thin-walled  cells  have  been  derived  from 
the  thick-walled  through  a  process  of  arrested  development.  The 
cause  of  such  alterations  is  to  be  sought  for,  and  it  will  doubt- 
less be  found  in  connection  with  another  component  of  the  ray. 
The  terminal  walls  of  the  ray  cells  present  three  typical  vari- 
ai.ons,  — (,)  thin-walled  and  entire,  (2)  thin-walled  and  locally 
thickened,  and  (3)  thick-walled  and  coarsely  pitted.^    The  first 

'  See  Appendix  A. 


8a 


ANAIOMY  OF  THE  (lYMNOSPKRMS 


feature  is  a  characteristic  of  5  2.6  per  cent  of  all  the  genera,  inclu- 
sive of  Gingko,  from  Dammara  to  Sequoia,  while  it  also  appears  in 
Cupressus  and  Abies  in  part  as  exceptional,  and  in  the  genus  Pinus 
to  the  extent  of  85.3  per  cent.  The  wall  presents  no  secondary 
growth  in  thickness,  either  locally  or  generally.  In  the  majority 
of  cases  it  crosses  the  line  of  the  principal  cell  axis  either  at  right 
angles  or  diagonally,  —  features  which  are  usually  of  very  second- 
ary value,  although  in  a  fe^'  ca^es,  as  Taxodium,  it  may  serve  a 
useful  purpose  as  an  associated  character  for  differentiation  from 
closely  allied  genera  (fig.  20).  In  other  cases  the  wall  is  more 
or  less  strongly  curved.    This  feature  is  prominent  in  Thuya, 

Cupressus,  Podo- 
carpus,  Thujopsis,  and 
Cryptomeria,  as  also  in 
the  more  highly  devel- 
oped hard  pines.  To 
a  less  extent  it  also  oc- 
curs in  Ta.\odium,  and 
it  constitutes  a  char- 
acter of  some  value  for 
differential  purposes 
(fig.  21). 

The  second  variant 
differs  from  the  first 
in  that  the  otherwise 
thin  wall  is  locally  thickened  (fig.  22),  the  secondary  growth 
forming  one  or  more  beaded  enlargements.  This  is  a  feature 
which  occuis  exceptionally  in  Abies,  Pseudotsuga,  Picea,  and 
Pinus,  but  it  is  typical  in  Cupressus  (66  per  cent)  and  Juniperus 
(72.7  per  cent),  where  it  constitutes  a  diagnostic  element  of  great 
value.  It  is  in  all  cases,  however,  to  be  regarded  as  a  transi- 
tional form  between  the  first  and  the  third  variant,  and  from  this 
point  of  view  it  also  possesses  a  somewhat  definite  phylogenetic 
value.  The  third  variant  is  characterized  by  a  marked  general, 
secondary  growth  of  the  wall,  which  thereby  becomes  more  or 
less  strongly  thickened  and  traversed  by  numerous  simple  pits 


Fu;.  21.  Thuya  GIGANTEA.  Medullary  ray  show- 
ing the  form  and  disposition  of  the  pits  on  the 
lateral  walls ;  the  thin  and  curved  terminal  walls ; 
the  cells  contracted  •    the  ends,    x  280 


MKI)L'J,I..\kV  RAYS 


83 


(fig.  23).  It  occurs  exceptionally  in  Juniperus  and  Pinus.  but  it 
IS  typical  m  Abies  (90.9  per  cent).  Tsuga  (100  per  cent),  Larix 
(100  per  cent),  and  Kcea  (90  per  cent).  In  Abies  and  Juniperus. 
where  transitional  forms  sometimes  occur,  the  walls  in  the  spring 


Fig  22^  CUPRESSUS  Macnabiana.    Medullary  ray  showing  the  form  and  position 
of  the  pits;  the  thin,  curved,  and  locally  thickened  terminal  walls,    x  280 

wood  may  be  only  locally  thickened,  but  in  such  cases  the  typ- 
ical feature  always  appears  in  the  summer  wood,  where  such 
secondary  alterations  are  most  strongly  emphasized. 

For  taxonomic  purposes  such  features  possess  a  definite  value. 
The  thick-walled  cells  of  Tsuga.  Larix,  and  Picea  p  rmit  of  an 


Fig.  23.  Juniperus  occidentaliS.  Medullary  ray  showing  the  form  and  dispo 
sition  of  the  pits  on  the  lateral  walls ;  the  thick  and  coarsely  pitted  termin  .1 
walls.    X  280 

easy  and  definite  segregation  of  these  three  genera  in  those  cases 
which  otherwise  might  involve  a  strong  element  of  doubt,  and 
the  same  rule  holds  true,  though  to  a  less  extent,  with  respect 
to  the  locally  thickened  walls  in  Cupressus  and  related  genera. 
Pits  on  the  lateral  walls  of  the  ray  cells  are  an  invariable 
feature  of  all  investigated  species  of  Gingkoales  and  Coniferales, 


84 


AN'ATO'  V  OF  THE  (lYMNOSl'ERMS 


including  fossil  reprc^atatives  and  the  Cordaitales.  They  vary 
very  much  in  form,  size,  and  number.  In  such  types  as  Junip- 
erus  they  are  most  diminutive  (fig.  23)  and  generally  numerous, 
while  in  many  of  the  pines,  such  as  P.  resinosa  or  P.  koraiensis 


Fig.  24.   PiNUS  refi.exa.    Medullary  ray  showing  („)  the  form  and  disposition 
of  the  pits  on  the  lateral  walls ;  {/>)  the  ray  tracheids.    x  280 

or  p.  reflexa  (fig.  24),  they  attain  to  maximum  3ize  and  occupy 
nearly  the  entire  surface  of  the  wall  within  the  limits  of  a  wood 
tracheid,  thereby  becoming  few  in  number.  In  Sequoia  (fig.  25) 
or  Taxodium  (fig.  20)  they  are  typically  oval,  in  Pinus  cubensis 


Fig.  25.   Sequoia  gigantea.    Medullary  ray  showing  the  form  and  disposition 
of  the  pits  or.  the  lateral  walls,    x  280 

or  P.  taeda  (fig.  26)  they  are  variously  lenticular,  while  in  P.  resi- 
nosa or  P.  koraiensis  they  are  oval  or  oblong,  or  even  quad- 
rangular. Such  variations  as  a  whole  are  far  more  numerous 
and  sharply  defined  in  Pinus  than  in  any  other  genus  known. 
In  all  the  investigated  genera  the  pit  is  bordered.    This  finds 


MKUUU^RV  kA\ 


S5 


either  partuil  or  complete  exceptions  in  the  geni-.s  Piniis  to  the 
extent  of  78.1  percent  of  the  spjcies,  in  which  the  pits  are  either 
simple  throughout  or  else  they  exhibit  a  more  ..r  less  definite  bor- 
der in  the  summer  wood  only.  That  a  border  is  a  characteristic 
feature  of  fossil  representatives  is  justified  by  comparison  with 
existing  species,  but  it  is  not  always  recognizable  in  consequence 
of  the  alterations  of  structure  due  to  the  general  process  of 
petrifaction.  Such  obliteration  not  infrequently  involves  the  pit 
orifice  also.  It  is  thus  apparent  that  such  structures  often  fail 
m  the  determination  of  fossils.    In  existing  species  the  border 


dentat...  walls;  (2)  the  structure  of  the  parenchyma  cells;  (3)  tracheids  con- 
t'  -mir.ous  with  parenchyma  cells,    x  280 

n  so  faintly  defined  as  to  be  difficult  of  recognition,  and 
especially  the  case  in  rays  of  a  resinous  character.  In 
such  cases,  however,  the  requirements  of  a  correct  diagnosis 
are  fully  met  by  the  pit  orifice.  The  general  law  of  development, 
then,  is  such  that  all  genera  except  Pinus  may  be  held  to  be 
characterized  by  bordered  pits.  Their  strong  tendency  to  obliter- 
ation in  that  genus  is  found  to  coincide  with  the  more  marked 
development  of  ray  tracheids,  which  undoubtedly  assume  more 
completely  the  original  functions  of  the  parenchyma  cells,  these 
latter  in  consequence  suffering  constant  structural  reduction,  as 
in  the  hard  pines. 


"f 


86 


ANATOMY  OF  THE  (lYMNOSPERMS 


In  the  distribution  of  the  pits  an  important  feature  appears  in 
the  numerical  variation  in  different  parts  of  the  ray.    Foi  diag- 
nostic purposes  it  is  necessary  to  have  reference  to  the  number 
of  pits  not   upon  the  entire  surface  of  an  individual  cell  but 
within  the  limits  of  a  spring  or  summer  tracheid,  as  the  case 
may  be.    They  are  invariably  most  numerous  in  the  region  of 
the  earliest  spring   tracheids,  usually  diminishing  toward  the 
summer  wood,  where  the  change  may  sometimes  take  place  ab- 
ruptly, and  in  which  they  are  most  commonly  reduced  to  one, 
with  occasional  obliteration  in  the  most  highly  modified  tracheids 
last  formed.    A  similar  law  of  distribution  is  applicable  within 
the  vertical  limits  of  the  ray.  When  these  structures  are  several 
cells  in  height  the  number  of  pits  is  typical,  and,  within  certain 
narrow  limits,  constant  for  all  except  the  marginal  cells.    Thus 
if  the  normal  number  is  one  to  two  for  the  central  cells,  it  may 
sometimes  rise  to  four,  si.x,  or  eight  in  the  marginal  cells  only, 
and  such  exceptions  must  be  noted  in  diagnosis.    When  the 
ray  is  only  one  cell  in  height  the  number  of  pits  agrees  with 
that  for  the  marginal  cells.    Such  numerical  variations  possess 
but  little  value  for  generic  purposes,  but  as  a  specific  character 
they  may  be  held  to  constitute  the  principal  differential  feature 
in  the  last  analysis.    These  relations  are  expressed  typically  in 
the  genus  Sequoia,  the  two  species  of  which  may  be  definitely 
differentiated.    S.  gigantea  is  characterized  by  oval  and  com- 
monly narrowly  bordered  pits,  the  broadly  oblong  orifice  eo-nl  to 
the  outer  limits  of  the  pit  and  chiefly  parallel  with  the  cell  .  ^is, 
one  to  two,  more  rarely  three  to  four,  per  tracheid.    In  some- 
what sharp  and  definite  contrast  to  this,  S.  sempervirens  has 
large,  oval,  narrowly  bordered  pits,  two  to  six  jjer  tracheid,  the 
round  or  broadly  oblong  orifice  being  cither  parallel  with  or  diag- 
onal to  the  cell  axis.    In  Libocedrus  the  pits  are  small,  narrowly 
bordered,  oval,  with  a  lenticular,  diagonal  orifice,  one  to  four 
per  tracheid.  Or  again,  in  Larix  americana,  the  pits  are  "  two  to 
six  per  tracheid,  becoming  distinctly  smaller  toward  the  summer 
wood  where  they  are  abruptly  reduced  to  two  and  finally  one 
per  tracheid."    In  Cupressus  pisifera  the  pits  are  "chiefly  two 


Mi:nui.i.Akv  ravs 


B7 


in  radial  series,  „r  in  fho  niarKinal  colls  and  low  rays  upwards 
..f  ..X  ,K-r  trachcid,-    In  Tax.Klium  distichum  the  pits  are  round, 
conapicuously  bordered,  and  br^e.  with  a  very  narrowly  lenticu- 
lar and  d>.„-onal  orifice,  which  is  often  as  long  as  the  outer  limits 
of  the  pit.    But  in  the  analytical  key  it  will  be  observed  that 
this  genus  is  naturally  brought  into  close  relations  with  Sequoia 
which  IS  also  distingu  ,hed  by  large  bordered  pits.    The  ulti' 
mate  differentiation  then  rests  upon  the  fact  that  in  the  latter 
the  pits  are  07'a/,  the  border  often  narrcw,  sometimes  odscun; 
while  the  03/o»^  or  lenticular,  usually  rather  broad,  orifice  is 
generally  parallel  with  the  cell  axis.    As  a  final  illustration,  the 
four  pits  of  Pinus  monophylla,  or  the  one  t<.  five  throughout, 
finally  reduced  to  one  to  two  in  the  summer  wood  of  V   Bal- 
fouriana,  point  with  much  definiteness  to  these  particular  si>ecies 
while  among  the  hard  pines  the  occurrence  of  large  oval  or 
squarish  pits,  one  or  rarely  two  per  tracheid,  segregates  a  group  of 
four  species.    Detailed  as  these  features  are,  they  are  not  acci- 
dental, but  of  such  constancy  as  to  admit  of  no  hesitation  in 
accepting  the  conclusions  to  which  they  point. 

The  length  of  the  ray  cell  is  subject  to  considerable  variation 
not  only  within  the  limits  of  an  individual  but  also  between  one 
si^ecies  and  another.  Our  studies,  however,  do  not  permit  the 
formulation  of  a  law  applicable  to  specific  differentiations,  even 
If  such  a  law  loes  exist,  which  present  evidence  leads  us  to  doubt  • 
but  det-  of  length,  in  terms  of  spring  tracheids,  have  been 
incorporr  .  m  all  the  diagnoses,  since  they  are  often  very 
suggestive  and  thus  may  assist  in  the  ultimate  recognition  of 
the  species. 

The  form  of  the  cell  is  of  more  evident  value,  although  too 
much  stress  must  not  be  laid  upon  it.  The  cell  is  either  straight 
as  in  Juniperus,  Libocedru.s,  or  Picea  (fig.  23),  or  it  becomes 
tusiform  through  contraction  of  the  extremities,  as  in  Cupressus 
Sequoia,  Taxodium,  etc.  (fig.  21).  As  a  well-defined  differentia! 
character  its  value  is  only  one  degree  higher  than  the  length  of 
the  cell,  and  for  the  ame  reason  it  has  been  introduced  into  the 
diagnoses  as  a  controlling  fa^^or  of  secondary  importance 


'II 


CMAi'TKR   VI 

MEDULLARY  RAYS  {continue,/) 
Rav  Tracmkids 

In  the  higher  Conifernc  the  mc(l"llary  ray  is  distinguished 
by  the  presence  of  an  element  which  differs  materially  in  its 
structure  from  the  associated  jarenchyma  <  ells.  These  elements 
have  been  designated  's  ray  tracluids  (13, 491-497).  Their  struc 
ture  is  so  peculiar,  and  they  present  such  important  rebtions 
to  classification  and  development  that  a  somewhat  detailed 
account  of  them  is  necessary,  to  some  extent  in  recapitulation  of 
well-known  observations  (13,  461  ;  81,  13  ;  82). 

As  stated  by  Ue  Bary,  the  ray  tracheid  resembles  the  paren- 
chyma cells,  from  which  they  differ,  however,  in  the  presence 
of  bordered  pits  on  all  their  walls.  Furthermore  such  pits  not 
only  differ  materially  in  form  and  size  from  the  bordered  pits 
of  adjacent  parenchyma  cells,  but  they  are  always  much  smaller 
than  the  pits  of  those  wood  tracheids  on  which  they  border. 
Such  tracheids  are  invariable  features  of  the  ray  in  all  the  higher 
Coniferac  from  Tsuga  and  Pseudotsuga  to  Pinus,  to  the  extent 
of  25  per  cent  of  the  investigated  genera.  In  Juniperus  tb  7 
occur  very  rarely,  being  found,  so  far  as  I  am  aware,  in  only  one 
species  (J.  nana)  out  of  a  total  of  eleven,  and  they  are  so  sparingly 
developed  as  to  readily  escape  observation.  In  Thuya  they  are 
to  be  met  with  in  T.  japonica,  likewise  in  a  rudimentary  state  of 
development.  Out  of  nine  species  of  Cupressus  they  occur  only 
in  C.  nootkatensis.  Of  the  ten  investigated  species  of  Abies  they 
are  found  only  i  onlsamea.    In  commenting  upon  this  fact 

many  years  smce  (13,  490),  it  was  also  pointed  out  that  among 
European  species  A.  e.xcelsa  is  similarly  exceptional,  but  no 
attempt  has  been  made  to  interpret  the  significance  of  such  facts. 

88 


MEDUILARV   RAYS 


«9 


In  Thuya.  Cupressus,  and  Abies  the  tracheids  are  strictly  mar- 
Kinal  in  the  composite  rays,  forming  the  entire  Htnicturc  in  ray^ 
only  one  or  two  elements  high.    This  ,  elation  obtains  in  all  the 
higher  Conifera;  in  the  first  instance ;  but  in  I  jrix,  I'icca.  and 
I'mus,  where  there  is  a  notable  increase  in  numbers,  they  also 
become  mterspersed  with  the  parenchyma  cells  and  eventually 
predommate  over  them,  a  feature  which  is  especially  character- 
istic  of  the  hard  pines.    Efforts  have  been  ma  le  to  show  that  in 
all  such  cases  the  two  kinds  of  elements  su     .ed  one  another  in 
a  definite  order  from  above  downward,  or      .  reverse,  but  our 
studies  have  failed  to  show  that  this  is  capable  of  practical  ap- 
plication  to  the  purposes  of  classification  or  even  of  phylogeny 
(13,  49I)-    The  pjeat  fact  of  importance  for  our  present  purpose, 
howe-er,  and  one  wl  -h  stands  out  with  much  prominence,  is  that 
the  ray  tracheids  are  ..ot  a  structural  feature  of  the  more  primi- 
tive C  oniferales,  but  only  of  the  higher  types,  such  as  Picea  and 
I'mus     Furthermore  the  primitive  position  for  these  structures 
IS  in  the  one-  or  two-celled  rays,  or  correspondingly  in  the  margins 
of  the  composite  rays. 

In  Thuya  and  Cupressus  the  tracheids  appear  to  stand  by  them- 
selves, and  they  exhibit  no  special  relations  to  the  parenchyma 
elements  which  would  permit  of  inferences  as  to  their  possible 
ongm.    In  the  genus  Pinus,  on  the  other  hand,  where  the  rela- 
tions are  somewhut  complex,  evidei..     does  appf      of  such  a 
nature  as  to  suggest  their  derivation.    In  Pinus  ino.      P.  Torrey- 
ana,  P.  pungens,  P.  clausa,  P.  taeda,  R  palustri.,,  an  J  P.  cubensis  we 
frequently  find  thick-walled  parenchyma  o.As  and  characteris- 
tic ray  tracheids  conterminous  '  ;,>  one  ano  K. ;.    This  does  not 
mean  a  simple  association,  sine       jarly  all  such  cases,  as  typ- 
ically presented  by  P.  palustris,  also  show  a  graduated  structure 
of  such  a  nature  as  to  confirm  the  belief  that  the  one  passes  into 
the  other  by  structural  gradations.    That  such  is  the  case  can- 
not be  doubted,  and  if  further  confirmation  were  n-eded,  it  is 
afforded  by  the  precisely  parallel  relations  to  be  met  with  in  the 
formation  of  resin  cells  and  resin  canals.    A  further  fact  of  much 
significance  from  the  standpoint  of  development  is  that  such 


go 


ANATOMY  OF  THE  GYMNOSPERMS 


interchangeable  relations  are  peculiar  to  the  highest  types  of  the 
genus  Pinus.  But  we  may  ask,  What  is  the  function  of  these 
structures  which  make  their  appearance  only  in  the  higher  Coni- 
fera;  ?  What  is  the  proper  significance  of  their  appearance  there, 
and  do  any  other  plants  offer  parallel  examples  ? 

In  the  so-called  medullary  rays  of  Lepidodendron  selaginoides 
(81,  141)  there  are  numerous  reticulated  or  spiral  elements  which 
are  undoubtedly  of  the  nature  of  tracheids,  and  they  may  be  held 
to  represent  theaucestral  form  of  theray  tracl  eids  in  the  Coniferae, 
toward  which  they  bear  the  same  relation  that  exists  between 
the  spiral  protoxylem  element  and  the  characteristic  wood  tracheid 
with  bordered  pits.  From  this  it  is  apparent  that  the  ray  tracheid 
of  Pinus  or  Tsuga  represents  a  primitive  structure  which  reappears 
in  response  to  conditions  of  growth  and  structural  alterations  of 
such  a  nature  as  to  demand  the  interposition  of  more  simple, 
because  more  primitive,  elements  for  the  proper  performance  of 
necessary  functional  activities.  These  activities,  in  the  case  of 
Lepidodendron,  are  probably  expressed  in  the  radial  distribution 
of  water  (81,  141),  and  we  are  no  doubt  correct  in  assuming 
similar  activities  to  be  carried  on  in  the  higher  Coniferae.  In  all 
those  species  which  present  the  primitive  structure  of  the  thin- 
walled  ray  cells,  both  fossil  and  recent,  there  are  no  tracheids  to 
be  found.  As  a  tendency  to  thickening  of  the  wall  arises,  there 
is  also  developed  a  sporadic  tendency  to  the  development  of  ray 
tracheids,  as  in  Thuya  and  Cupressus.  It  is  also  a  noteworthy 
fact  that  simultaneously  with  a  general  thickening  of  all  the  cell 
walls  throughout  the  ray,  as  in  the  genus  Tsuga,  ray  tracheids 
become  a  constant  and  prominent  structural  feature.  This  rela- 
tion exists  in  Pseudotsuga,  Larix,  Picea,  and  Pinus,  and  it  is  a 
remarkable  fact  that  as  the  type  of  organization  advances,  and 
the  structural  modifications  of  the  wall  become  more  profound, 
the  tracheids  gain  steadily  in  numbers  and  importance  until  they 
finally  replace  the  parenchyma  cells  more  or  less  completely. 
Such  facts  serve  to  direct  attention  to  the  idea  that  by  such  pro- 
gressive alteration  the  ray  cells  gradually  lose  their  normal 
functional  powers  with  respect  to  the  radial  distribution  of  water, 


MEDULLARY  RAYS  g, 

and  under  such  circumstances  it  is  imperatively  demanded  that 
this  deficiency  should  be  met  through  some  other  structures 
Under  these  circumstances  two  alternatives  are  possible  :  first 
that  the  thick-walled  and  useless  cells  should  return  to  their 
primitive  condition  in  opposition  to  the  general  course  of  devel- 
opment, and  once  more  resume  their  appropriate  functions.    Such 
structural  reductions  do  in  reality  occur  in  these  very  cases,  as 
shown  in  Pinus  taeda,  etc.,  but  it  is  to  be  observed  that  they  are  of 
the  nature  of  a  growth  which  has  been  arrested  at  such  an  early 
stage  as  to  be  devoid  of  many  of  the  normal  structural  features 
Furthermore  it  would  be  difficult,  if  not  impossible,  to  obtain  evi- 
dence from  other  plants  in  support  of  a  hypothesis  of  this  nature 
It  is  true  that  in  the  case  of  girdled  pines  the  heartwood  may 
resume  an  activity  long  since  lost,  and  thus  take  upon  itself  once 
more  the  function  of  the  sapwood,  and  also  to  some  extent 
the  function  of  the  bark ;  but  such  renewed  functional  power 
does  not  in  any  way  involve  structural  modifications  of  existing 
elements,  and  cases  of  this  sort  cannot  be  cited  in  support  of  the 
hypothesis.    It  is  therefore  fair  to  conclude  that  such  structural 
reduction  and  restoration  of  functional  activity  are  accompanied 
by  a  partial  diversion  of  energy  to  the  preponderant  tracheids. 

The  second  alternative  permits  us  to  consider  that  in  the 
ordinary  course  of  development  the  ray  cells  gradually  lose  their 
functional  activity  as  a  result  of  extreme  structural  modification, 
and  that  this  loss  of  power  cannot  be  restored,  even  though  the 
wall  may  return  to  a  primitive  condition  of  structure  through 
various  phases  of  atrophy.    In  accordance  with  this  idea  the 
tracheid  would  be  introduced  as  the  most  natural  because  the 
original  medium  for  such  activities  as  are  centered  in  the  ray, 
and  it  would  therefore  acquire  additional  importance  both  nu- 
merically and  functionally  in  direct  proportion  to  the  loss  of 
power  experienced  by  the  parenchyma  cells.    This  appears  to  be 
a  reasonable  interpretation,  and  in  the  light  of  observed  facts 
It  would  seem  to  be  the  correct  one. 

A  structural  feature  of  great  importance  in  the  ray  tracheid 
appears  in  certain  inequalities  of  the  upper  and  lower  walls,  which 


f 


92 


ANATOMY  OF  THE  GYMNOSPERMS 


take  the  form  of  teethlike  projections  into  the  cavity  (fig.  26). 
In  what  may  be  regarded  as  the  most  highly  developed  tracheids 
the  teeth  project  across  the  cell  cavity  until  they  meet  and 
coalesce,  thereby  forming  a  more  or  less  definite  reticulation, 
which  gives  to  the  tracheid  a  very  characteristic  appearance. 
As  seen  in  tangential  section,  such  reticulations  often  appear  as 
narrow  bands  crossing  the  cavity  from  side  to  side,  Vhys  giving 
the  cell  a  varying  aspect.  Such  dentate  and  reticulated  tracheids 
are  absolutely  confined  to  the  second  section  of  the  genus  Pinus, 
in  which  they  constitute  one  of  the  most  characteristic  features 
to  the  extent  of  68.3  per  cent  of  the  species.  A  more  detailed 
analysis  of  this  feature,  as  applied  to  the  hard  pines,  is  desirable. 
In  P.  resinosa  and  P.  Thunbergii  the  tracheids  are  simply  dentate. 
In  six  species,  represented  by  P.  Murrayana,  the  teeth  extend  into 
definite  reticulations  confined  to  the  summer  wood ;  but  in  six 
other  species,  represented  by  P.  Jeffreyi,  such  reticulations  are 
sparingly  developed  throughout  the  ray.  In  P.  taeda  a  transitional 
form  appears.  Typically  this  species  shows  the  tracheids  to  be 
sparingly  reticulated,  but  occasionally  they  are  strongly  reticulated 
throughout.  This  brings  to  mind  the  further  fact  that  in  all 
species  which  are  sparingly  reticulated  there  is  a  marked  tend- 
ency to  strong  reticulation  in  the  summer  vvood.  In  the  thirteen 
remaining  species  the  tracheids  are  uniformly  strongly  reticu- 
lated throughout  the  extent  of  the  ray,  and  this  feature  attains 
its  highest  expression  in  P.  palustris  and  P.  cubensis.  It  is  there- 
fore manifest  that  we  n'e  to  deal  here  with  a  graduated  develop- 
ment of  such  a  natLie  that  the  simply  dentate  tracheid  is  the 
most  rudimentary,  while  the  strongly  reticulated  is  of  the  most 
advanced  type  of  structure. 

The  value  of  the  ray  tracheid  for  taxonomic  purposes  depends 
upon  (i)  its  occurrence  in  certain  genera,  and  (2)  its  structural 
peculiarities.  In  the  great  majority  of  cases  1  e  simple  wall  of 
the  tracheid  affords  no  basis  of  specific  differeiitiation,  but  in  the 
various  forms  of  dentate  and  reticulated  walls  of  the  second  sec- 
tion of  Pinus  it  is  of  well-defined  value  in  this  respect.  Pinus 
resinosa,  P.  Thunbergii,  and  P.  koraiensis  are  all  characterized 


MEDULLARY  R^"S 


93 


by  the  occurrence  of  simple  teeth,  v/hich  are  sometimes  sparingly 
developed.  This  feature  is  intimately  associated  with  the  occur- 
rence of  large,  simple,  and  single  pits  on  the  lateral  walls  of  the 
ray  cells.  From  this  group  P.  densiflora  may  be  differentiated  by 
the  reticulations  in  the  tracheids  of  the  summer  wood.  Among 
the  hard  pines  P.  taeda  is  distinguished  by  ray  tracheids,  which  are 
typically  sparingly  reticulated  throughout,  but  on  the  other  hand 
P  palustris  and  P.  cubensis,  which  probably  represent  the  highest 
types  of  the  genus,  are  at  once  separated  from  all  other  species 
by  reason  of  the  extent  to  which  reticulations  ^re  developed 

The  relations  which  the  tracheids  bear  to  the  parenchyma 
cells  in  the  general  composition  of  the  ray  also  have  an  impor- 
tant bearing  upon  specific  differentiations.    In  the  genus  Tsuga 
the  tracheids  are  sometimes  interspersed,  affording  the  first 
instance  of  a  relation  which  later  becomes  most  prominent  in  the 
higher  genera,  and  the  same  relation  is  also  expressed  in  Pseudo- 
tsuga  and  I.arix.   In  Picea  there  is  a  somewhat  stronger  tendency 
to  an  mterspersal  which  is  only  expressed  fully  in  Pinus.    In  the 
soft  pines  eleven  out  of  thirteen  species  show,  as  in  the  previ- 
ous genera,  that  the  tracheids.  as  a  rule,  are  rarely  interspersed; 
P.  aristata  forming  a  partial  exception,  as  shown  in  a  sparing  in- 
tersixTsal.    P.  monophylla  and  P.  monticola.  on  the  other  hanH 
show  a  strong  interspersal  of  the  tracheids,  and  in  this  respect 
they  approach  the  hard  pines.    In  the  latter  group  we  again  find 
the  first  four  species  characterized  by  a  rare  interspersal ;  but 
passing  on  to  the  more  highly  c'n'eloped  species,  such  types  as 
P  clausa,  P.  palustris,  and  P.  glabra  show  that  the  interspersed 
tracheids  are  not  only  numerous  but  also  that  they  eventually 
become  conspicuously  predominant  and  often  constitute  the  bulk 
of  the  ray  structure.    It  is  evident,  then,  that  such  features  pos- 
sess an  obvious  value  for  diagnostic  purposes,  particularly  in  the 
genus  Pinus,  where  the  variations  are  numerous,  well  defined, 
and  applicable  to  particular  species  or  groups  of  species. 

As  displayed  in  tangential  section,  the  medullary  ray  exhibits 
two  principal  forms,  each  of  which  presents  features  of  great 
taxonomic  and  phylogenetic  value.    The  type  of  structure  which 


9^ 


ANATOMY  OF  THE  GYMNOSPERMS 


prevails,  and  which  may  be  regarded  as  the  fundamental  form  of 
the  ray,  is  that  of  from  one  to  many  cells  superimposed  in  a  single 
series  of  varying  height  (fig.  27).  Such  one- 
seriate  rays  are  characteristic  features  of  all  the 
investigated  recent  genera.  In  30  per  cent  of 
the  genera  there  is  a  sporadic  tendency  to 
a  multiseriate  form  as  expressed  in  the  devel- 
opment of  rays  which  ire  two-seriate  in  part. 
Such  enlargement  is  not  confined  to  any  partic- 
ular portion  of  the  structure,  and  within  the 
limits  of  the  same  section  it  may  arise  at  the  cen- 
ter or  at  either  end.  It  is  never  found  in  /\bies, 
Picea,  or  Pin  us,  but  it  is  met  with  m  Pseudotsuga 
macrocarpa,  three  species  of  Cupressus,  two  of 
Juniperus,  one  each  of  Sequoia  and  Araucaria, 
and  two  of  Larix  (figs.  27, 
28).  In  Libocedrus  such 
tendency  is  much  more  pro- 
nounced, and  the  rays  may 
be  described  as  two-  to 
three-seriate  in  part. 
Fig.  27.  Sequoia  This  feature  is  of  so 
sEMPERviRENs.    sporadlc  a  nature  that 

showing  a  typically    satisfactory  evidence  as  to 
one-seriate  ray  of    j^g  origin  or  significance, 

broad  form.    >.  280     ,  ,  ^ 

but  reference  to  Cordaites 
tends  to  throw  some  light  upon  this  somewhat 
obscure  problem.  In  fourteen  species  of  Cor- 
daites, three  of  which  are  European  (28, 606- 
609),  it  is  seen  that  the  rays  present  four 
variants  ranging  from  the  strictly  one-seriate 
form  to  one-  to  two-,  rarely  three-seriate. 
The  distribution  is  in   the  following  percentage  proportions: 


Fig.  28.  Taxus  brevi 
Foi.iA.  Tangential 
view  of  a  medullary 
ray  showing  ics  two- 
seriate  character. 
X  280 


1-2,  rarely  3-seriate   21.4  percent   I   2-seriate  in  part 
j-2,       seriate      .     14.3  "     "      I   i-seriate      .    . 


50.0  per  cent 
14.3   «     « 


MEDULLARY  RAYS 


95 


0    0 


From  this  it  would  appear  that  Cordaites  as  a  whole  approaches 

the  primitive,  multiscriate  ray,  such  as  may  be  found  in  the 

Cycads,  much  more  nearl>  ihan  any  of  the  existing  species  under 

consideration,  and  from  this  point  of  view  it  becomes  possible 

to  arrange  a  sequence  showing  the  relative  development  in  the 

following  terms:  (i)  Cordaites.  (2)  Libocedrus. 

(3)  all  other  genera,  as  enumerated  above.  The 

evidence  of  fossil  plants,  however,  shows  that 

caution  must    be  exercised  in  cur  estimate 

of  what  constitutes  the  primitive  ray.    The 

structure  of  Stigmaria  shows  a  preponderance 

of  one-seriate  medullary  rays  (81,  224),  and 

that  such  are  primitive  rays  cannot  well  be 

doubted.    In  general,  however,  we  are  pi     - 

ably  not  far  from  correct  in  the  assumptk.n 

that  -.he  highest  form  of  the  ray  is  expressed 

in  if,  one-seriate  character.    Deviations  from 

this  uould  then  require  to  be  interpreted  as 

vestigal  features,  which  indicate  a  relatively 

lower  ivpe  of  orgr-.nization  in  direct  propor- 
tion to  the  increase  of  a  tendency  toward  a 

multiseriate  form. 

In  the  majority  of  species  the  side  walls  of 
the  parenchyma  cells  are  thick  and  traversed 
by  small  pits.    In  the  genus  Pinus  the  wall 
is  commonly  thin,  and  it  closes  the  orifice  of 
a  very  large  pit  on  the  wall  of  the  adjacent 
wood  tracheid.    This  is  notably  true  of  the 
soft  pines,  in  which  the  .side  wall  either  pro- 
jects as  a  convex  membrane,  or  it  is  concave 
and  curves  into  the  cell  cavity.     Such  a  feature  is  of  very  little 
if  any  importance  except  in  P.  reflexa,  where  the  thin  side  walls 
almost  invariably  project  so  as  to  give  the  cells  a  correspond- 
mgly  mflated  appearance  (fig.  29).    It  is  not  only  apparent  in  a 
tangential  section,  but  is  very  conspicuous  in  the  transverse  sec- 
tion (fig.  1 8).  where  the  inflated  walls  are  seen  to  project  into  the 


'0. 


Fic.  29.  Pi  MS  RE- 
Fl.KXA.  Tangeii'ial 
.section  of  a  r.iedui- 
lary  ray  slunvir,  (he 
typically  inrtated 
cells.    X  ^CX3 


Jf  M 


96 


11  £  f 


Fig.  30.    PSEUDOTSUGA 

DouGLASii.  Tangen- 
tial section  of  a  fusi- 
form ray  showing  (a) 
the  typical  resin  ca- 
nal with  thick-walled 
epithelium,  but  devoid 
of  thyloses.    x  280 


ANATOMV  OF  THE  GYMNOSPERMS 

cavities  of  adjacent  wood  tracheids,  thereby 
giving  to  the  ray  a  beaded  appearance.  As 
an  exceptional  variation  it  possesses  no  ap- 
parent significance  with  respect  to  questions 
of  descent. 

The  second  frrm  of  the  ray  is  t'uit  which 
has  been  designated  as  fusiform  in  refer- 
ence to  its  characteristic  outline  (44,  39). 
Such  rays  occur  in  relatively  few  of  the 
existing  genera  to  the  extent  of  20  per 
cent.    They  occur  typically  in  Pseudotsuga, 
larix,  Picea,  and  Pinus,  and  they  are  thus 
seen  to  be  characteristic  of  the  most  ad- 
vanced types.    Among  extinct  species  they 
are  unknown  except  in  the  case  of  Sequoia 
Burgessii  (46,  42-46)  and  S.  Penhallowii  of 
Jeffrey  (25,  321),  in  which  they  present  a 
remarkable  exception  to  the  general  course 
of  development  and  structure  of  that  genus. 
The  fusiform  rays  are  peculiar  in  their 
structural  features.    They  vary  greatly  in 
height  as  between  different  genera,  and 
such  variations  also  occur  within  a  given 
genus,  the  extremes  being  met  with  in  the 
genus  Pinus,  where  P.  palustris  and  P.  pon- 
derosa  present  the  antithetic  relations. 
In  most  cases  they  are  much  higher  than 
the  one-seriate  rays  with  which  they  are 
associa  ed,  but  this  rule  is  subject  to  sev- 
eral exceptions.    They  are  always  distin- 
guished by  a  broadening  of  the  central  tract 
by  from  two  to  several  times  the  original 
dimensions,  thereby  becoming  more  or 
less  multiseriate.    These  variations  depend 
upon  the  nature  of  the  included  structure, 
which  exhibits  modifications  directly  related 


MEDULLARY  RAYS 


97 


to  progressive  development  of  the  genus.   Such 
broadening  arises  abruptly  in  Pseudotsuga, 
Larix,  and  Picea,  so  that  the  terminals  above 
and  below  consist  of  a  single  series  of  cells 
with  the  general  structure  of  the  one-seriate  ray 
(fig.  30).    In  Pinus  the  broadening  is  less  ab- 
rupt, diminishing  in  both  direc 
tions  somv;what  gradually,  thus 
giving  rise  to  a  region  of  lenticu- 
lar form  which  occupies  upwards 
of  half  th(  height  of  the  ray,  or 
in  son  e  caser,  constitutes  the 
entire  atructunj.    From  this  it 
follows  that  in  such  types  as 
P.  palustris  (fig.  3 1,  B)  the  termi- 
nals, which  are  often  prolonged 
to  gre-t  length,  may  be  linear 
and  one-seriate,  while  in  P.  pon- 
derosa  the  whole  ray  is  lenticular 
in  outline  and  the  terminals  con- 
sist of  only  one  or  .  wo  limiting 
tracheids  (fig.  32).    Within  the 
region  oi  the  central  tract  the 
cells  are  all  thick-walled  in  Pseu- 
dotsuga, Larix,  and  Picea,  but  in 
Pinus   they  are  genen.lly  thin- 
walled,  and  in  the  hard  pines  this 
fe- cure  is  emphasized  by  a  degen- 
eration of  the  tissue  to  such  an 
extent  that  it  is  readily  broken 

P  ~       "        out  in  making  sections,  whence 

>-ic..3i,A.  Pinus  ALBicuALis.   Tan-    ;»  ^i,„,      *•.-,, 
genual  section  of  a  fusiform  ray    "  Characteristically  appears 

Stl  VnTSVaT.i^rXcl'^'ut'ci     '''^'!  """"'^  ^'■°'^^"  "^  °^  ^"^'''^ly 
parenchyma,    x  280;  B.  Pinus  pa-    Wanting.    The  principal  feature 

I.USTRIS.  Tangential  sm-lini.  „<o  *.,..:  r  ,  .       . 


'<! 


/ 


■usTRis.  Tangential  section  of  a  fusi-    of  such  ravQ    :,nrl  »V,»  ^„^      u-  u 
form  ray  in  part  showing  thin-walled  ^^y^'  ^""^  ^"^  ""^  ^^^ich 

parenchyma  broken  out.    x  280 


determines  their  form,  is  the 


98 


ANATOMY  OF  THE  GYMNOSl'ERMS 


C..4 


presence  of  a  resin  canal  in  each  case.  Such  resin  canals  traverse 
the  ray  continuously  for  its  en*'  e  length. 
They  present  the  same  details  of  structure 
as  the  resin  canals  which  lie  within  ihe 
xylem.  In  Pseudotsuga,  Larix,  and  I'icca 
the  central  canal  is  narrow,  espechlly  in 
the  first  two  genera,  and  the  epithelium 
consists  of  a  single  layer  of  thick-wallcd 
cells.  In  Pseudotsuga  and  Larix  (fig.  30) 
thyloses  are  altogether  wanting,  but  in 
Picea  they  are  of  sporadic  occurrence. 
In  Pinus  (figs.  31  and  32),  on  the  con- 
trary, the  canals  are  always  distinguished 
by  their  great  breadth  ;  the  epithelium  is 
composed  of  from  one  tc  several  rows  of 
thin-waP  ■..  cells,  which  are  often  resinous 
and  often  much  disorganized,  while  thy- 
loses are  an  invariable  feature  of  the 
central  canal. 

A  comparison  of  different  genera  and 
species  shows  that  there  is  a  somewhat 
striking  variation  in  the  number  of  one- 
seriate  rays  (tangential)  to  a  given  area  of 
section.  Such  variations  may  arise  within 
narrow  limits  in  the  same  species,  accord- 
ing to  location  and  conditions  of  growth, 
but  apart  from  this  there  are  somewhat 
constant  variations  between  different  spe- 
cies, which  may  be  expressed  by  the  use 
of  the  relative  terms  "few"  and  "many." 
No  attempt  has  been  made  to  define  such 
variations  more  exactly,  but  it  is  quite  pos- 
sible that  a  determination  of  the  averaj^c 
number  to  a  square  centimeter  or  other 
convenient  unit  might  disclose  a  somewhat  greater  differential 
value  than  is  at  present  apparent.    A  simple  illustration  will 


6..\ 


Fig.  32.  Pinus  CLAUSA. 
Fusiform  ray  showing 
(a)  the  resin  canal  with 
thyloses;  (#)  thin-walled 
parenchyma  cells;  {c) 
the  terminals  composed 
of  only  one  or  two  tra- 
cheids.    x  280 


MEDULLARY  RAYS 


99 


Z^Lf       T         '  °'  '■''  '^^''•"  "'"'^'^^  '^^^'  ^'"«  O^  this 
Character.    In  Taxus  cusp.data  the  rays  are  numerous,  while  in 

he  two  remaining  species  they  are  relatively  few.   The  «me 

feature  applies  to  the  differentiation  of  Torreya  nucifera  from  the 

other  species  of  that  genus.    In  Pinus  clausa, 

P.  serotina,  P.  Murrayana,  etc.,  the  same  rule 

applies,  but  in  all  such  cases  it  cannot  be  ac- 
cepted as  final. 
The  height  of  the  ray  is  subject  to  such  varia- 

tions,  even  within  the  same  species,  that  it  can- 
not be  defined  with  sufficient  accuracy  to  admit 

of  Its  application  to  classification  in  more  than 

a  very  general  sense.    It  is  true  that  the  rays 

of  Gingko  are  always  low.  while  those  of  Taxus 

and  Torreya  are  often   high.    In  Junipcrus 

they  are  commonly  low,  while  in  Pinus  they 

range  from  low  to  very  high.    Such  variations 

do  not  possess  sufficient  constancy  to  admit 

of  either  generic  or  specific  application  in  the 

strict  sense,  though  they  not  infrequently  serve 
a  useful  purpose  as  controlling  fi.ctors.  and  they 
are  therefore  incorporated  in  all  the  diagno- 
ses.  Variations  in  breadth  have  a  much  more 
definite  value,  since  the  element  of  constancy 
IS  well  defined.    The  genus  Thuya  (fig.  33) 
may  almost  invariably  be  differentiated  by  this 
feature.    In  Cupress-is,  C.  thyoides  may  be  dis- 
tinguished by  a  similar  feature,  while  C.  arizo- 
nica  and  C.  Goveniana  are  equally  well  indicated 
by  their  great  breadth.    The  same  rule  applies 
also  to  Juniperus,  Sequoia  (fig.  27).  Pinus,  and 
other  genera,  whence  it  appears  that  this  feature 

unnn  TT  ""^  J  ^'  ''  "'^"^'  "''°^^^^^  ^^''h  and  dependent 
upon  the  form  of  the  component  cells  (tangential),  which  affords  a 
means  of  Q:st,n^ru,shing  genera  and  species  with  much  directness. 
The  narrowly  oblong  cells  of  Thuya  (fig.  S3)  serve  to  separate 


Fig.  33-  Thuya 
c.iCANTEA.  Tan- 
gential section  of 
a  ray  showing  the 
typicalJy  narrow 
and  oblong  cells. 
X  280 


/     •3 
■I' 


lOO 


ANATOMY  OF  THE  (.YMNOSPEkMS 


this  genus  without  difficulty,  since  a  similar  feature  occurs  but 
rarely  elsewhere,  and  then  in  such  association  as  to  make  the 
differentiation  clear.  In  Juniperus  the  genus  is  separable  into 
four  well-marked  divisions:  (i)  round  to  oval  or  transversely 
oval,  (2)  rays  broad,  the  cells  oval  to  round,  chiefly  round; 
(3)  chiefly  oval ;  (4)  rays  narrow,  the  cells  oblong  to  oval,  chiefly 
oblong.  The  broadly  oval  and  thin-walled  cells  of  Sequoia  sepa- 
rate it  from  associated  genera.  In  Picca  the  genus  may  be  sub- 
divided according  as  the  cells  arc  (i)  variable,  round,  oval,  or 
oblong;  (2)  equal  and  uniform,  oblong  or  oval.»  Cupressus  is 
simihrly  separable  into  groups.  But  it  is  not  difficult  to  separate 
C.  arizonica  and  C.  Goveniana  more  specifically,  by  reason  of 
their  broad  rays  and  very  conspicuously  transversely  oval  cells, 
from  C.  pisifera  with  its  round  or  oval  cells  and  C.  thyoides  with 
its  narrow,  oblong,  rarely  oval  cells.  In  the  genus  Pinus  atten- 
tion is  at  once  directed  to  P.  Murrayana  by  the  conspicuously 
round  or  transversely  oval,  very  unequal,  and  variable  cells. 

The  interspersal  of  the  tracheids  often  imparts  a  characteristic 
appearance  to  the  tangential  aspect  of  the  ray,  especially  in  the 
genus  Pinus,  and  more  particularly  among  the  hard  pines.  In 
this  group  the  tracheids  present  very  variable  forms  and  sizes. 
In  such  types  as  P.  glabra  they  are  small,  oval,  or  round,  and 
wherever  they  occur  they  give  rise  to  a  marked  local  contraction. 
In  P.  palustris  and  P.  cubensis  they  are  commonly  oblong  and 
not  infrequently  they  become  several  times  higher  than  broad. 
As  they  are  almost  invariably  narrower  than  the  associated 
parenchyma  cells,  they  cause  a  local  contraction  which  sometimes 
e.xtends  over  considerable  distances.  In  P.  palustris  the  predomi- 
nance of  the  tracheids  is  carried  so  far  that  the  rays  are  chiefly 
composed  of  them,  and  it  then  becomes  appropriate  to  apply 
the  term  "  interspersed  "  to  the  few  parenchyma  cells.  In  all 
of  the  more  highly  organized  rays  of  the  hard  pines  the  appear- 
ance of  the  structure  is  so  complex  and  variable  that  a  proper 

>  The  term  "  equal "  here  applies  to  cells  of  the  same  ray  which  are  of  the  same 
width,  "  uniform  "  to  the  cells  of  all  rays  which  are  pretty  constantly  of  one  form, 
the  contrasting  terms  being  "  unequal"  and  "variable  "  respectively. 


MEDULLARY  RAYS 


lOI 


Generic. 


diagnosis  can  be  drawn  .,  ly  when  wc  take  cognizance  of  the 
principal  aspects  presented,  nn.l  these  arc  sometimes  as  many 
as  four  in  number.  ' 

A  consideration  of  the  various  structural  features  thus  dis- 
cussed m  their  relations  to  cbssification  will  show  that  no  other 
portion  of  the  stem  possesses  so  many  elements  of  importance  as 
the  medullary  ray,  which,  in  consequence,  attains  the  highest 
value  m  this  respect  and  affords  differential  characters  of  wide 
range,  great  prominence,  and  easy  recognition,  and  is  of  primary 
importance  in  the  differentiation  of  groups,  genera,  and  species  • 
and,  as  a  general  summary,  the  utility  .,f  these  characters  for  such 
purposes  is  approximately  indicated  in  the  following  tabulation  : 

1.  Rays  (tangential)  of  two  kinds. 

2.  Ray  tracheid.<i. 
Pits  on  tiie  lateral  walls  of  the  ray  cells  simple  or  bordered 
Terminal  walls  of  the  ray  cells  thin  and  entire  or  locally- 
thickened. 

Form  and  character  of  the  ray  cell  (tangential). 
Form  and  size  of  pits  on  the  lateral  walls  of  the  ray  cells. 
7-  Ray  tracheids  dentate  or  reticulated. 

8.  Direction  and  form  of  orifice  of  pits  on  the  lateral  walls  of 

ray  cells. 

9.  Upper  and  lower  walls  of  ray  cells. 

10.  Ray  tracheids  interspersed  or  marginal. 

1 1.  Di.sposition  of  pits  (radial). 

12.  The  number  of  pits  per  tracheid. 

The  marginal  cells  of  the  ray  —  that  is,  those  which  terminate 
the  ray  above  and  below,  as  seen  either  in  a  radial  or  a  tangential 
section  — are  usually  somewhat  different  from  those  which  cor- 
stitul  ^  the  bulk  of  the  structure.  This  difference  is  expressed  in 
a  tangential  section  by  their  greater  height  and  relatively  narrower 
form.  In  a  radial  section  it  is  expressed  by  the  greater  height, 
the  somewhat  thinner  walls,  and  the  sinuous  form  of  the  latter  as 
they  conform  to  the  terminations  of  adjacent  tracheids.  In  such 
deviations  from  the  usual  characteristics  of  the  ray  cells  it  is 
probable  that  those  of  the  margin  may  be  held  to  exhibit  a  tend- 
ency to  the  formation  of  ray  tracheids  of  which  they  would 


3. 
4- 

6. 


■  Specific. 


I03 


ANATOMY  OF  THK  GYMNOSPERMS 


therefore  be   regarded   as  potential   fornii.    This   view  pains 
strength  from  the  fact  that  the  ray  trachcids  fir>t  apjKar  in  just 
those  situations ;  that  when  they  arc  iiioradic,  as  in  Abies  hal- 
samca,  they  are  ;ntcrs{K'rsc'(l  and  conterminous  with  the  marginal 
cells  ;  thai  their  external  forms  and  general  aspect  are  the  seme ; 
and  that  when  the  trachcids  are  fully  developed  and  become 
constant  features  of  the  ray  it  is  at  the  expense  rf  the  ordinary 
marginal  cells,  which  then  disappear.    Furthermore  Jeffrey  has 
shown  that  in  Sequoia  Penhallowii  (as),  where  the  marginal  cells 
assume  a  very  characteristic  form,  they  are  also  interspersed  in 
the  higher  rays  precisely  as  tracheids  are  in  the  rays  of  the  higher 
Conifer.TB.    Another  feature  of  these  cells  —  to  which  Jeffrey 
has  directed  attention  in  Sequoia  Penhallowii  ~  is  the  presence  of 
numerous  crystals.    This  is  unique  among  the  Sequoias,  and  it 
is  unknown  in  any  other  genus  of  the  Coniferales  except  Abies, 
where,  as  Jeffrey  also  shows,  a  similar  deposit  of  crystals  is  to 
be  met  with  in  A.  concolor,  A.  grandis,  A.  bracteata,  A.  nobilis, 
and  A.  magnifica;  but  it  is  a  feature  of  much  more  sporadic 
occurrence,  since  large  areas  of  these  species  show  no  t  rystals, 
while  in  Sequoia  Penhallowii  they  are  exceedingly  abundant. 
Jeffrey  correctly  regards  this  as  indicating  a  certain  relationship 
between  these  two  genera  (25).  a  connection,  however,  which  is 
also  indicated  by  other  structural  features,  as  pointed  out  by 
Penhallow  some  years  since  (44.  45). 


CHAPTER  VII 

MEDUI.MRV  RAVS  {conHnurd) 

Relations  to  Development 

We  arc  now  in  a  p<»»itk.n  to  determine  the  relations  in  which 
the  various  structural  features  of  the  medulLry  ray  stand  to 
development,  and  for  this  purpose  it  may  be  most  convenient 
to  discuss  them  i-,  that  sequence  which  is  apparently  consonant 
with  the  general  jrder  of  evolution  of  the  entire  group 

It  has  been  ascertained  that  bordered  pits  are  characteristic 
features  of  the  lateral  walls  of  the  ray  cell  in  72.4  per  cent  of  the 
investigated  species. and  that  in  theremaining27.6per  cent.among 
the  higher  types,  simple  pits  predominate,  but  a  closer  scrutiny 
of  this  latter  group  discloses  some  features  of  mo-e  than  passing 
.merest.    Reference  to  the  table  of  anatomical  data  (Appendix  A) 
will  show  that  the  change  from  bordered  tr  simple  pits  is  entirely 
confined  to  the  genus  Pinus.  and  that  it  does  not  arise  abruptly 
as  if  m  response  to  some  unusual  condition  whereby  a  profound 
alteration  in  the  usual  course  of  develooment  was  iniuced  •  but 
■t  IS  effected  by  stages,  showing  that  whatever  influen-^es  were 
l>rought  to  bear,  they  operated  gradually  through  a      .newhat 
pro  onged  period  of  development,  while  here  and  there  strong 
tendencies  to  reversion  were  manifested,  and  that  the  alteration 
was  finally  effected  in  a  permanent  way.  only  in  the  most  highly 
cifveloped  pines.    Commencing  with  P.  Lambertiana,  it  will  be 
observed  that  some  species  of  the  soft  pines  are  characterized  by 
-".mple  pits.    Among  the  hard  pines  P.  clausa  and  P.  rigida  have 
bordered  pits,  while  the  si.x  following  species  again  show  simple 
P'ts.    We  next  come  to  a  group  of  four  species,  with  one  excep- 
tion  (P.  Murrayana)  Japanese,  in  which  there  is  a  mingling  of 
botli  bordered  and  simple  pits,  showing  a  decided  persistency 

103 


•■I  ^  ,■  '■ 

;■   -  i  ;.i 
*''   I". 


104 


ANATOMY  OF   IHE  GYMNOSPERMS 


of  the  primitive  character  in  the  face  of  conditions  which  involve 
a  change.  Following  these  are  two  species  with  simple  pits,  one 
with  transitional  features,  five  with  simple  pits,  one  with  bor- 
dered pits,  one  with  the  transitional  form,  and  the  remaining  six 
species  with  simple  pits  only.  It  will  therefore  be  seen  that  these 
changes  occur  in  waves,  and  that  within  the  limits  of  forty-one 
species  there  are  three  complete  and  six  incomplete  recurrent 
phases.  If  we  were  arguing  from  purely  theoretical  grounds,  all 
of  these  species  should  be  arranged  in  such  order  as  to  show  (i) 
bordered  pits,  (2)  transitional  forms,  and  (3)  wholly  simple  pits, 
and  we  should  thereby  gain  a  perfect  developmental  sequence. 
But  such  a  position  would  not  be  justified  by  other  evidence  of 
an  equally  if  not  more  weighty  character,  and  it  is  our  object 
to  interpret  the  facts  as  they  arc  found.  It  has  already  been 
shown  that  the  occurrence  of  simple  pits  in  the  pines  is  conso- 
nant with  a  higher  type  of  development,  and  that  the  change  is 
not  only  accompanied  by  sporadic  reversions  or  survivals,  as  one 
may  choose  to  regard  them,  but  that  the  change  as  a  whole  is 
a  process  of  reduction.  From  this  point  of  view,  then,  we  must 
regard  the  occurrence  of  bordered  pits  in  P.  clausa,  P.  rigida,  and 
P.  pungens  as  pure  survivals  of  a  more  primitive  structure,  —  a 
feature  which  is  less  perfectly  expressed  in  such  transitional  forms 
as  P.  koraiensis  or  P.  inops.  But  a  mere  mingling  of  the  two 
kinds  of  pits  in  the  same  species  is  not  the  only  evidence  in  this 
direction.  The  mingling  of  simple  and  bordered  pits  does  nut 
occur  indiscriminately,  but  in  accordance  with  a  well-defined  law 
to  the  effect  that  the  former  are  characteristic  of  the  spring  wood 
throughout  its  entire  extent,  while  the  latter  occur,  if  at  all,  only 
in  the  summer  wood,  where  they  might  be  expected,  since  tiic 
arrested  development  which  might  be  complete  in  the  case  of 
relatively  thin-wallcd  cells  could  be  readily  overcome  in  part  in 
walls  of  greater  secondary  growth.  This  in  no  way  conflicts  with 
the  observed  fact  that  in  the  majority  of  cases  the  usual  course 
of  development  is  such  that  the  bordered  pits  of  the  spring  wood 
very  commonly  become  reduced  to  simple  pits  in  the  summer 
wootl,  in  accordance  with  De  Bary's  law,  as  already  stated  in 


MEDULLARY  RAYS 


»05 


application  to  other  cases.    Constancy  in  the  structure  of  such 
pits  has  been  found  to  be  characteristic  of  Cordaites,  Gingko  the 
laxacea-,  and  all  the  lower  forms  of  the  Conifera..  from  which 
we  may  conclude  that  the  bordered  pit  is  essentially  a  primitive 
character.    On  the  other  hand,  variation  is  a  well-marked  feature 
of  the  pit  m  the  genus  Pinus,  as  first  e.xpressed  in  the  large  oval 
or  squarish  and  open  pits  of  P.  resinosa  or  P.  Thunbergii,  and 
as  later  appears  with  greater  frequency  in  the  smaller  and  very 
inconstant  pits  of  P.  ta^da  or  P.  palustris.    Such  variations,  then, 
involving  a  gradual  and  complete  transformation  to  the  condition 
of  simple  pits,  are  characteristic  only  of  the  more  highly  developed 
pines,  from  which  it  may  be  concluded  that  it  is  a  feature  con- 
sistent with  a  relatively  high  order  of  development  in  exact  accord 
with  the  principles  governing  parallel  changes  in  the  pits  of  the 
wood  tracheids.    They  are  also  in  harmony  with  the  well-known 
principle  that  variation  is  always  of  a  more  simplified  form  in 
primitive  types,  but  that  it  tends  to  greater  diversification  with 
advance  in  organization  and  general  development,  as  a  necessary 
sequence  to  the  adjustment  of  the  organism  to  a  wider  and  more 
complex  environment.    Finally,  it  has  been  shown  that  the  elimi- 
nation of  the  bordered  pit  proceeds  concurrently  with  the  more 
complete  organization  of  the  ray  tracheids.  in  response  to  a  sub- 
stitution of  functional  activities  between  these  structures  and  the 
degenerate  parenchyma  cells.    We  may  therefore  conclude  that 
extreme  variation  in  the  character  of  the  pit  is  an  expression  of  a 
liighcr  type  of  development,  and  that  from  this  standpoint  such 
structures  have  a  definite  value  in  solving  questions  of  descent. 
I  he  terminal  walls  of  the  ray  cells  present  three  variants  with 
■xspcct  to  secondary  growth.    All  the  more  primitive  Cordai- 
tales  and  Coniferales  are  characterized  by  thin  walls.  Cupressus 
and  Juniperus  are  chiefly  distinguished  by  their  thin  walls,  which 
arc  also  locally  thickened,  a  feature  which  has  been  shown  to  be 
due  to  incipient  secondary  growth.    But  such  alterations  are 
already  foreshadowed  in  Liboccdrus,  where  the  local  thickening 
of  the  wall  is  of  a  sporadic  nature.    In  Abies  magnifica  and  A. 
i^^andis  there  is  a  partial  recurrence  of  thin  and  locally  thickened 


h  % 


1 06 


ANATOMY  OF  THE  GYMNOSPERMS 


walls,  which  is  pretty  fully  expressed  in  A.  concolor.  A  similar 
recurrence  is  met  with  in  Pseudi)tsiiga  macrocarpa,  in  Picea 
polita,  and  in  Pinus  Parrayana,  and  it  is  also  complete  in  thirteen 
of  the  most  highly  developed  species  of  Pinus,  where  the  walls 
have  suffered  extreme  degeneration.  Within  the  limits  of  Picea 
(i)  and  the  soft  pines  (5)  there  are  six  instances  in  all  of  spo- 
radic and  partial  survival  of  the  thin  and  locally  thickened  wall. 
The  first  tendency  to  thick  and  strongly  pitted  walls  is  mani- 
fested in  five  species  of  Juniperus,  and  such  development  is  fully 
expressed  in  what  may  be  regarded  as  the  three  most  highly 
developed  species.  Thick  walls  are  then  fully  characteristic  of 
Abies,  —  with  a  partial  reversion  in  A.  concolor,  —  of  Tsuga, 
Pseudotsuga  Douj;'asii,  and  Picea,  with  the  exception  of  P.  polita, 
five  species  of  soft  pines,  and  three  species  of  hard  pines.  In 
P.  toeda  and  P.  pauistris  the  walls  are  so  degenerate  that  their 
structure  cannot  be  satisfactorily  determined,  but  they  arc  pre- 
sumably thin-walled. 

From  these  facts  it  is  manifest  that  the  progressive  thickening 
of  the  terminal  walls  accords  with  the  general  course  of  devel- 
opment, and  once  more  making  use  of  tne  principles  already 
applied  to  the  pits  on  the  lateral  walls,  we  are  brought  to  the 
natural  conclusion  that  (i )  an  increase  in  the  thickness  of  the  walls 
is  evidence  of  a  higher  type  of  organization,  and  (2)  that  the 
sporadic  recurrence  of  thin  walls  with  local  thickenings  represents 
the  persistence  of  a  primitive  character. 


Ray  tracheids  probably  constitute  one  of  the  most  valuable 
of  the  structural  elements  as  an  indication  of  development.  This 
has  its  foundation  (i)  in  the  fact,  previously  shown,  that  they 
arise  as  secondary  structures  from  the  parenchyma  elements, 
with  which  they  exhibit  interchangeable  relations,  in  direct  re- 
sponse to  the  requirements  of  a  higher  degree  of  organization, 
and  (2)  in  their  general  relation  to  progressive  development. 
The  complete  absence  of  ray  tracheids  from  the  Cordaitales  and 
Gingkoales,  as  also  from  the  Taxaccae  and  more  primitive  Coni- 
fera?,  while  they  arc  invariable  features  of  the  higher  Conifera-, 


MEDULLARY  RAYS 

107 

in  which  they  attain  their  most  complete  development,  admits 
of  only  one  mterpretation.    The  fact  that  they  are  exclusively 
features  of  the  Conifera.  emphasizes  their  inferior  value  for  Z 
termmmg  the  derivation  of  that  group,  while  it  points  to  their 
supenor  importance  as  a  factor  in  the  sequence  oi  the  various 
coniferous  genera.    They  occur  sporadically  in  Thuya  (,)    Cu- 
pressus  (3).  Juniperus  (,).  and  Abies  (1).    They  are  prominent 
features  of  Tsuga.  Pseudotsuga.  Larix,  Picea.  and  Pinus.    Thei 
invarable  absence  from  Sequoia  would  appear  to  suggest  that 
this  genus  ,s  more  primitive  than  Thuya,  but  there  are  other 
reasons  which  serve  to  suggest  the  opposite  relation.    Apart 
from  this  exception,  it  will  be  seen  that  in  accordance  withVhe 
relations  exhibited  in  the  table  of  anatc.mical  data  (Appendix  A) 
the  genera  enumerated  form  a  continuous  series,  commencing 
..th  those  showmg  sporadic  tracheids  and  ending  with  those  in 
which  such  structures  attain  their  highest  expression.    From 
this  we  are  justified  in  the  conclusion  that  the  rare  occurrence 
of  tracheids  in  Thuya,  etc..  is  to  be  interpreted  as  the  first  evT 
dence  of  a  tendency  in  development  which  is  only  fully  realized 
at  a  later  period,  and  this  appears  to  be  justified  by  a  closer 
exammation  of  the  last  five  genera  in  this  respect,  since  it  is 
found  that  in  them  the  tracheids  not  only  show  a  progressive 
numerical  development  but   their   structure  likewise  becomes 
more  complicated  in  direct  relation  to  the  evolution  of  higher 
ypes  of  genera  and  species.    We  must  therefore  I^ok  upon  the 
tracheids  with  their  thin,  simple  walls  as  the  .nmitive  form. 
while  those  with  the  strongest  reticulations  are  of  the  highest 
t) :    ,  -he  two  being  united  by  a  transitional  form  characterized 
by  the  presence  of  simple  teeth.    The  evidence  at  hand  -'oes 
not  appear  to  justify  the  idea  that  the  various  genera  have  been 
segregated  into  small  groups  representing  side  lines  of  develop- 
n^ent.  but  it  rather  favors  the  thought  that  each  genus  is  in 
>t^^e.f  a  complete  short  line  of  descent,  and  that  among  these  a 
prominent  parallelism  has  arisen  in  the  tendency  toward  the 
development  of  tracheids.  -a  tendency  which  has  been  carried 
to  completion  in  the  case  of  only  five  of  the  series,  and  in  such 


m 


io8 


ANATOMY  OF  THE  GYMNOSPERMS 


a  way  that  in  only  a  portion  of  one  of  these  has  that  completion 
reached  its  highest  expression. 

The  occurrence  of  two  kinds  of  parenchyma  ray  cells  is  an 
exclusive  feature  of  the  genus  Pinus,  and  its  value  for  phyloge- 
netic  purposes  is  strictly  confined  to  the  relations  of  the  various 
species  of  pines.  The  first  appearance  of  this  differentiation  is 
among  the  soft  pines  in  P.  aristata  and  P.  edulis.  It  is  to  be 
observed,  however,  that  the  thick-walled  cells  are  always  domi- 
nant, the  thin- vailed  cells  being  interspersed  amo-<g  and  con- 
terminous with  them.  No  further  evidence  of  such  structural 
alterations  is  to  be  noted  until  we  reach  the  more  highly  devel- 
oped representatives  of  the  hard  pines.  Among  these  definite 
transition  forms  occur  in  P.  Murrayana,  P.  Coulteri,  P.  Jeffrey!, 
P.  virginiana,  P.  insignis,  and  P.  cubensis,  while  in  P.  arizonica, 
P.  ponderosa,  P.  Sabiniana,  P.  pungens,  etc.,  the  original  relations 
are  e.xactly  reversed  and  the  thick-walled  cells  show  a  diminish- 
ing frequency  until  in  P.  glabra  and  P.  taeda  they  are  rare>;  met 
with.  Such  facts  give  effective  proof  of  the  belief  that  struc- 
tural alteiations  of  this  nature  are  not  only  evidences  of  the 
highest  type  of  development  among  the  pines  but  also  among 
the  Coniferales  as  a  whole. 

The  invariable  absence  of  the  fusiform  rays  from  all  except 
the  four  genera  which  attain  the  highest  structural  development, 
and  their  constant  occurrence  in  rxU  the  species  of  such  genera, 
presents  an  argument  of  great  force  as  showing  their  relation 
to  the  evolution  of  advanced  types.  There  is  here  no  evidence 
of  sporadic  development,  foreshadowing  the  general  course  of 
evolution,  but  the  fusiform  rays  with  their  resin  canals  appear 
abruptly  and  permanently.  Among  fossil  plants  —  except  the 
genus  Pityoxylon,  which,  being  essentially  Pinus,  falls  under  tlie 
general  rule  —  there  is  no  instance  of  such  structures  outside 
of  the  four  genera  named,  save  in  the  case  of  the  remarkable 
Sequoia  Burgessii,  from  the  Lignite  Tertiary  (51,  42),  and  S.  Pcn- 
hallowii  of  Jeffrey  (25).  As  it  will  be  necessary  to  further 
discuss  the  essential  structure  of  the  fusiform  ray,  we  need  not 
deal  with  it  more  in  detail  at  the  present  moment. 


:rn 


CHAPTER  VIII 
WOOD  PARENCHYMA 

In  our  present  studies  we  recognize  as  wood  parenchyma  all 
those  elements  which,  in  association  with  tracheids.  hav.  their 
major  axes  extended  parallel  with  the  principal  axis  of  growth  • 
and  which,  V   accordance  with  accepted  limitations,  are  charac- 
cr.zed  by  thcr  more  or  less  cylindrical  form,  abrupt  termina- 
tions and  relatively  thin  walls.    Such  elements  do  not  occur  in 
wood  of  the  Cordaitales,  and  they  are  infrequent  in  the  Ging- 
koales,  but  they  are  somewhat  conspicuous  features  of  the  Coni- 
fcrales,  where  they  acquire  great  prominence  either  because  of 
thcr  peculiar  contents  or  their  association  with  somewhat  highly 
speca  ized  tissues.    They  differ  in  their  structure  as  in  their 
special    unctions,  though  in  the  main  they  are  connected  with 
the  production  of  resinous  matter;  and  inasmuch  as  their  mo^^t 
prominent  feature  is  usually  found  in  associated  products  of  cel- 
lular activity,  it  will  be  most  convenient  to  discuss  them  under 
specific  names,  which  may  serve  to  direct  attention  to  their  par- 
ticular purposes  in  the  plant  economy.    They  may  therefore  be 
classified  as  follows :  j       j  ^  u^ 

Wood  parenchjTtia : 

a.  Crj-stallogenous  i(''oblasts. 

b.  Resin  celLs. 


#S.S 


CrVSTALLOGENOUS    J     .OBLASTS 

The  investigations  of  Eichlcr  (15,  35)  show  that  in  Gin^'  -^ 
the  wood  IS  characterized  by  the  presence  of  wood-parenchyma 
col  s,  which  take  the  form  of  short  idioblasts  of  lenticular  form 
m  longitudinal  section,  and  are  distinguished  by  the  storage  of 
crystals  of  calcium  oxalate.    Such  structures  are  peculiar  to  this 

109 


no 


ANATOMY  OF  THE  GVMNOSPERMS 


genus,  in  which  they  form  a  specific  character  of  definite  value, 
and  it  is  therefore  of  importance  that  they  should  be  described 
somewhat  in  detail. 

In  a  transverse  sectioi  (plate  i8)  the  idioblasts,  recognizable 
by  their  conspicuous  crystals,  may  be  seen  scattered  through 
the  entire  section  without  special  reference  to  either  the  spring 
or  the  summer  wood.  Under  a  high  t  ^ree  of  amplification  it 
will  be  seen  that  they  are  often  single,  but  quite  frequently  they 

are  grouped  in  radial  series 
of  ttvo  or  three,  in  which  case 
one  is  generally  much  larger 
than  the  others  (fig.  34,  a). 
The  form  is  narrowed  tangen- 
tially  and  extended  radially  so 
^  as  to  be  approximately  lenticu- 

a^'^^/iTT)  Id'^\        ^^^'  ^^^  ^^^  cavity  is  usually 

Wk^^L-^  Ik?J?^^'     pretty  well  filled  with  a  com- 

pound crystalline  mass.  The 
idioblast  is  situated  in  the 
line  of  one  of  the  radial  rows 
of  tracheids,  the  continuity  of 
which  it  interrupts.  It  is  usu- 
ally much  larger  than  the  in- 
dividual wood  trachcid,  from 
which  it  also  differs  in  the  char- 
acter of  the  cell  wall,  which  is 
very  thin  and  not  infrequently 
.shows  a  want  of  continuity  suggestive  of  obliteration  in  the  course 
of  development.  In  a  radial  section  the  idioblasts  are  usually  of 
an  isodiametric  form,  more  rarely  elongated  longitudinally,  and 
the  compound  crystalline  mass  somewhat  more  than  half  fills  the 
cavity.  In  this  section  the  walls  are  seen  much  better  than  ir 
any  other,  and  the  relations  of  the  idioblasts  to  one  another  are 
well  exhibited.  In  a  tangential  section  (fig.  34,  l>)  the  wall  is  also 
well  displayed.  The  individual  idioblasts  are  lenticular  in  form 
and  the  crystalline  mass  completely  fills  the  cavity  transversely, 


ikai- 


Fig.  34.  GiNcvo  niLOBA.  a,  trans- 
verse section  showing  the  occurrence 
and  form  of  a  crystallogenous  idio- 
blast ;  i,  tangential  section  of  the  same, 
tr.,  tracheids;  /r.ii'.,  tracheid  walls;  /., 
idioblast;  iw.,  idioblast  wall;  i>:, 
crystals,    x  233 


RESIN  CELLS  ,,, 

but  only  about  half  fills  it  longitudinally.  This  section  is  the  most 
useful  for  displaying  the  relations  of  the  idioblasts  to  the  adjacent 
tracheids,  inasmuch  as  the  limits  of  the  walls  of  the  latter  are 
much  more  clearly  defined.  As  seen  i..  the  tange    ial  section,  the 
Idioblasts  fall  into  a  single  longitudinal  series,  which  may  not 
embrace  more  than  two  or  three  members,  but  more  commonly 
there  are  upwards  of  twency^ne  in  a  series.    Not  infrequently 
the  Cham  of  crystals  will  be  found  to  be  interrupted  for  some 
httle  distance,  but  the  continuity  of  the  idioblasts  will  then  be 
seen  to  be  uninterrupted  through  the  development  of  cylindrical 
elements  of  uniform  but  smaller  diameter  and  devoid  of  crystals 
from  which  it  would  appear  that  the  lenticular  or  rounded  form! 
as  determined  by  the  particular  plane  of  section,  is  not  the  normal 
form  of  the  cell,  but  that  such  special  form  results  from  the 
growth  of  the  crystal,  which  must  have  been  deposited  when  the 
tissue  was  in  a  formative  stage  of  development.    This  is  made 
apparent  in  another  very  striking  manner.    In  any  tangential 
exposure  of  such  a  series  it  may  be  seen  that  the  terminal  mem- 
ber does  not  necessarily  occupy  all  the  space  between  the  walls 
of  adjacent  tracheids.    There  is  thus  developed  an  intercellular 
space  of  variable  dimensions,  which  may  be  quite  small  or  may 
be  so  extensive  as  to  suggest  that  the  crystals  were  formed  in 
such  spaces  and  not  in  closed  cells.    Such  spaces  are  obviously 
not  the  result  of  that  splitting  which  is  ordinarily  incident  to  the 
growth  of  tissues,  but  they  clearly  arise  as  a  secondary  effect 
incident  to  the  development  of  the  crystalline  mass  and  the 
pressure  of  this  latter  upon  the  surrounding  parts. 

Resin  Cells' 

In  a  large  proportion  of  the  Coniferales  the  wood  is  character- 
ized by  the  presence  of  more  or  less  numerous  wood-parenchyma 
cells.  The.se  are  always  distinguished  by  their  cylindrical  form 
and  transverse  terminations.  They  are  invariably  associated 
with  the  production  of  resin,  either  as  entering  into  the  com- 
position of  resin  passages  or  as  isolated  cells.    It  is  this  latter 


112 


ANATOMY  OF  THE  GYMNOSPERMS 


group  with  which  we  arc  most  particularly  concerned  at  the 
present  moment,  and  as,  with  very  few  exceptions,  they  are 
uniformly  characterized  by  the  presence  of  resin,  which  gives 
them  a  distinctive  appearance,  I  prefer  to  describe  them  as  resin 
cells  rather  than  by  the  more  commonly  employed  designation 
of  zvood  parenchyma,  which  conveys  no  suggestion  of  their 
special  function  and  most  prominent  feature. 

The  resin  cells  are  found  to  be  entirely  wanting  in  those 
species  of  Taxus  (4)  and  Torreya  (3)  which  are  included  in  the 
present  studies.  They  do  occur,  however,  in  Podocarpus,  where 
they  present  the  usual  structural  features,  but  they  are  there 
remarkable  for  their  number  and  the  great  abundance  of  massive 
resin  which  they  contain.  This  distribution  in  the  Ta-xaceae  does 
not  altogether  accord  with  the  conclusions  of  Eichler  (15,  35), 
who  states  that  they  occur  very  sparingly  in  the  Taxaceae,  but 
makes  no  mention  whatever  of  their  presence  in  Podocarpus, 
where  they  are  much  too  prominent  to  escape  even  the  most 
casual  observation. 

In  the  Conifer.x  resin  cells  are  characteristic  of  all  genera 
except  Picea  and  Pinus,  where  they  are  replaced  by  resin  pas- 
sages, of  which  they  form  essential  parts.  They  are,  therefore, 
features  in  the  wood  structure  of  twelve  genera,  and  they  are 
constant  characteristics  of  all  their  species,  with  very  few  excep- 
tions. Such  exceptions  apply  exclusively  to  the  genus  Abies, 
in  which  four  species  —  A.  Frascri,  A.  lasiocarpa,  A.  Veitchii, 
and  A.  balsamea  —  are  wholly  devoid  of  such  structures. 

The  recognition  of  the  resin  cells  presents  no  difficulty  in 
the  great  majority  of  cases,  because  of  the  abundance  and  depth 
of  color  of  the  resinous  contents.  This  finds  its  most  complete- 
expression  in  Taxodium,  Sequoia,  Cupressus,  etc.  In  Abies,  on 
the  other  hand,  where  these  cells  have  experienced  extreme 
numerical  reduction,  and  where  there  also  seems  to  be  a  cor- 
responding reduction  in  their  secretory  power,  it  is  impossible 
to  recognize  them  in  this  way.  In  such  cases  it  is  often  pos- 
sible to  distinguish  them  by  their  slightly  different  form  and 
somewhat  thinner  walls  as  compared  with  the  adjacent  wood 


RESIN  CELLS 


"3 


tracheids,  by  their  situation  slightly  in  advance  of  the  outermost 
row  of  summer  wood  tracheids.  and  most  particularly  by  their 
pitted  terminal  walls  when  the  latter  lie  near  the  pbne  of  sec- 
tion.   This  last  feature  may  also  be  relied  upon  in  all  other 
cases  when  any  element  of  doubt  is  involved  (fig.  35)     in  longi 
tudinal  section  the  characteristic  form  of  the  cell  serves  to  dis 
tmguish  it  beyond  all  doubt,  even  in  the  absence  of  resinous 
contents.   Whether  exposed  in  radial  or  tangential  section  the  cell 
has  the  form  of  a  narrow  cylinder  upwards  of  300  m  in  length 
and  always  several  times  longer  than  broad,  except  in  cases  where 


F.o.  35.  AB.ES  AMABius.   Transverse  section  showing  .he  position  and  structure 
of  the  resm  cells  (r...)  on  the  outer  face  of  the  summer  wood,    x  joo 

there  is  a  definite  tendency,  through  aggregation,  to  the  forma- 
tion of  resin  canals. 

The  resin  cells  sometimes  occur  in  pairs,  but  more  generally 
as  isolater'  structures  separated  by  one  or  more  tracheids  The 
termmal  \valls  are  transverse  and  more  or  less  strongly  marked 
with  simple  pits.  The  side  walls,  especially  the  radial,  are  pro- 
vided with  simple  pits,  though  often  few  in  number,  and  this 
eature  serves  to  a  large  extent  to  assi.st  in  their  differentiation 
from  adjacent  tracheids  of  similar  form  (fig.  36,  r).  It  neverthe- 
less not  infrequently  happens  that  in  transitional  forms,  such 
as  are  met  with  in  Sequoia  sempervirens  (fig.  36,  c),  bordered 
pits  occur  on  the  lateral  walls. 

The  resin  is  in  all  cases  massive  and  often  very  abundant 
In  such  genera  as  Taxodium  (plate  30)  or  Sequoia  (plate  36)  it 


is**"! 


114 


ANATOMY  OF  THE  GYMNOSI'KRMS 


completely  fills  the  entire  cell  cavity,  but  in  I^rix,  Tsiiga,  and 
Pseudotsuga  it  takes  the  fornt  of  a  pcriphctal  layer  in  imme- 
diate contact  with  the  inner  face  of  the  cell  wall  (plate  44). 
The  reduction  thus  indicated  is,  in  some  species,  carried  to 
such  an  extent  that  the  resin  is  barely  recognizable,  while  in 

Abies  it  is  wholly  wanting. 

A  relation  of  more  than  ordi- 
nary interest  is  that  of  the  resin 
cells  to  certain  forms 
of  tracheids.    In  Se- 
quoia scmperv'ircns  it 
commonly  happens 
that  the  resin  cells 
lie  in  immediate  con- 
tact with  tracheids  ot 
special  form.    These 
structures  are  wholly 
unlike  the  wood  tra- 
cheids among  which 
they  are  found,  but 
they  are,  in  all  essen- 
tial respects,  like  the 
tracheids  of  the  med- 
ullary  rays.     They 
have  the  form  of  long, 
cylindrical  elements 
with  abrupt  termina- 
tions, and  they  thus 
bear  an  external  re- 
semblance in  form  to  the  wood-parenchyma  cells  with  which 
they  are  associated.    They  differ,  however,  in  the  distinguish  in;,' 
presence  of  bordered  pits  upon  their  side  and  terminal  walls 
(fig-  37>  «)•    The  relation  of  these  two  elements  is  nevertheless  a 
much  more  intimate  one  than  is  implied  by  mere  association. 
In  Sequoia  an  interchangeable  relation  is  manifested,  as  already 
pointed  out,  in  the  occurrence  of  resin  cells  with  bordered  pits 


Fig.  36.  Sequoia  sem- 
PERVIRENS.  Kadial 
sections  showing  (</) 
the  form  of  the  resin 
cells  and  the  associ- 
ated parenchyma  tra- 
cheids; (/>)  resin  cells 
from  the  spring  wood 
showing  the  form  of 
the  resin ;  (<•)  resin  cells  showing  transitional 
forms  with  bordered   pits,   x  200 


RESIN  CELLS 


"5 


(fig.  36).  while  ,n  Abies  amabilis  (fig.  37)  resin  cell,  and  tra- 
cheids  al«.  form  a  conterminous  scries.    It  is  thus  obvious  that 
we  have  here  precisely  the  same  interchangeable  relations  that 
have  been  found  to  occur  in  the  medullary  rays,  and  it  is  evi- 
dent the  one  element  must  arise  through  modification  of  the 
tl\J     P"-^^;**  order  of  this  sequence  is  not  altogether  clear 
from  the  available  data,  but  the  fact  that 
ray  trr  '  Ms  are  derived  from  their  asso- 
ciated pau.ichyma  cells,  and  that  in  such 
types  as  Podocarpus,  Taxodium,  etc.,  the 
resin  cells  occur  without  tracheids,  while 
the  latter  do  occur  in  Sequoia  and  espe- 
cially in  Abies,  scorns  to  justify  the  infer- 
ence that  here  also  they  a-e  derived  forms, 
having  their  origin  substantially  in  special 
modifications  of  the  parenchyma  elements. 
In  view  of  these  relations  it  is  necessary  to 
distinguish  such  elements  as  parenchyma 
tracheids  in  order  to  establish  their  proper 
identity  and  differentiate  them  from  the 
wood  tracheids  which  have  a  wholly  dif- 
ferent origin,  as  well  as  from  the  ray 
tracheids  which  have  a  wholly  different 
location.    It  is  probable  that  the  paren- 
chyma tracheids  also  serve  a  similar  pur- 
pose to  the  ray  tracheids  with  respect  to 
the  distribution  of  nutrient  fluids.    The 
origin  of  the  parenchjma  tracheids  as  sug- 
gested finds  support  in  the  statement  of 
Kichler  (is)  that  the  wood  parenchyma  arises  through  the  activity 
of  the  cambium  cells,  abundantly  in  the  Cupressinea;  and  Abie- 
tineas,  formmg  in  exceptional  cases  the  epithelium  of  the  resin 
can -lis,  since  it  at  the  same  time  shows  how  the  parenchyma 
tracheids  arise,  and  how  they  may  be  intimately  connected  with 
the  wood  parenchyma  ;  but  it  finds  additional  support  in  a  knowl- 
edge of  the  genesis  and  structure  of  the  resin  passage. 


Fig.  37.  Abiks  amahii.is. 
Radial  section  showing 
(a)  the  structure  of  the 
parenchyma  tracheids; 
((*)  the  structure  of  the 
resin  cells ;  a  and  b  being 
normally  conterminous. 

X   2CX3 


a- 


i\ 


Il6 


anatonIy  ok  the  (;ymnosi'krms 


In  Sequoia  and  Abies  we  have  two  genera  which  arc  remark- 
able for  their  transitional  forms  of  structure,  affording  a  fairly 
cle;ir  conception  of  the  genesis  of  the  resin  passage.    In  each 
case  there  is  a  well-defined  tendency  toward  the  aggregation  of 
the  resin  cells  into  compact  groups  which  take  the  form  of  lon- 
gitudinal strands,    inclosed  on  all  sides  by  the  accomfxinying 
iwrenchyma  tracheids.    Under  such  circumstances  the  individiuil 
cells  undergo  a  continual  reduction  in  length  until  they  eventu- 
ally become  but  two  or  three  times  longer  than  broad,  or  they 
may  even  become  isodbmetric.    This  change  is  not  accompa- 
nied by  any  alteration  in  the  thickness  of  the  walls  in  the  earlier 
s   .«      of  development,  but  as  a  result  of  such  a  shortening  the 
effect  is  to  bring  about  the  concentration  of  a  greater  number 
of  simple  pits  within  a  given  area.    Such  cells,  therefore,  are 
always  more  strongly  pitted  than  those  which  are  isolated  and 
of  grc«ater  length.    When  aggregates  of  this  sort  have  attained 
to  a  certain  degree  of  development  a  line  of  cleavage  arises  in 
the  center  of  the  mass  and  results  in  the  formation  of  an  inter- 
cellular .space  which,  according  to  ICichlcr  (15),  always  arises 
schizogenously.    This  space  is  short  and  either  isodiametric  or 
but  little  longer  than  broad,  the  length  coinciding  with  the  prin- 
cipal a.xis  of  growth.  Such  cystlike  reservoirs  or  sacs  represent 
the  primitive  form  of  the  resin  canal,  aufl  t^^v  arc  typically 
developed  in  Sequoia,  Abies,  and  Tsuga.    They  always  fcjrm  a 
continuous  series  extending  in  a  direction  jjarallel  with  the  axis 
of  growth  ;  but  as  the  type  of  organization  advances,  they  merge, 
forming  a  continuous  canal  such  as  may  be  f<>und  typically  in 
Pseudotsuga  or  Pinus.    From  these  statements,  then,  it  is  clear 
that  the  parenchymatous  resin  cells  undergo  modification  in  two 
directions,  passing  into  parenchyma  tracheids  on  the  ont  hand, 
and  on  the  other  becoming  shorter  and  shorter,  according  to 
conditions  of  aggregation,  until  they  pass  into  .short  cells  which 
eventually  constitute  the  epithelium  structure  of  the  somewhat 
complicated  resin  passage,  the  latter  thereby  becoming  the  ex- 
pression  of  a   peculiar  aggregation   of   resin   cells.    Whatever 
the  stage  of  development  may  be,  the  resin  passage  is  always 


RKSIN  CKILS 


found  to  he  composed  of 


117 


ictiiral  elements  arranged  in  the 
lunowinK  or.icr  lr.>m  without  t.,ward  the  center  :  (,)  mrcnchvma 
trachei,ls.  (.)  rein  cells  eventually  forming  an  epithelium/and 
(3)  the  central  reservoir  i,.  the  form  of  a  cyst  or  canal  This 
structure  .s  fully  exemplified  in  the  genus  Pinus.  where  the 
highest  form  of  development  is  attained 

While  the  occurrence  of  resin  cells  in  particular  genera  is  a 
feature  of  great  taxonomic  value,  their  importance  in  this  res,)ect 
.s  greatly  emphasized  by  the  particular  form  of  their  distribution 
and  the  constant  tendency  they  exhibit  toward  the  formation* 
of  definite  aggregates.    In  Thujopsis  (plate  24)  and  Crypto- 
merui  (plate  26)  the  resin  cell ,  are  always  scattered  through- 
out  the  entire  transverse  secti       and  they  show  no  tendency  to 
the    ormation  of  aggregates.    ...  I'odocarpus.  where  there  is  a 
notable  increase  in  numbers,  the  same  general  law  of  segregation 
prevails,  but  there  is  nevertheless  a  somewhat  well-defined  tend- 
ency toward  aggregation.    In  Thuya  66.6  per  cent  of  the  s,,ecies 
show  definitely  scattering  cells.  33.3  per  cent  show  the  cells  to 
l.e  scattering  with  a  tendency  toward  a  more  comjKict  dispo- 
sition, while  in  33.3  per  cent  the  cells  fall  into  well-defined  aggre- 
gates or  an  approximation  to  such  an  arrangement     The  genus 
Sequoia  IS  characterized  chiefly  by  the  widely  scattering  distri- 
biition  of  the  resin  cells  (plate  36).  but  in  S.  sempervirens  there 
are  indivdual  cases  in  which  there  is  also  a  definite  aggregation 
'nto  groups.    In  Cuprcssus  53.9  per  cent  of  the  species  are  dis- 
tmguished  by  the  presence  of  widely  scattering  cells,  which  be- 
come definitely  arranged  in  zones  m  38.4  per  cent,  and  aggre- 
gated into  groups  in  ^7  per  cent  of  the  species.    It  will  be 
observed  here  that  this  feature  of  distribution  is.  on  the  whole 
more  pronounced  in  the  relatively  primitive  genera,  and  that  it' 
diminishes  in  force  in  the  genera  of  a  relatively  high  order 

In  Taxodium  (plate  30)  and  Libocedrus  (plate  32).  both  of 
which  are  distinguished  by  the  presence  of  very  prominent  resin 
cells,  these  structures  are  disposed  in  well-defined  .  >nes  which 
are  concentric  with  the  growth  rings  and  lie  either  in  the  spring  or 
summer  wood,  or  in  both.    This  is  to  be  interpreted  as  a  definite 


h 


Ii8 


ANATOMY  OF  THE  GYMNOSPERMS 


tendency  to  aggregation,  which  is  nevertheless  not  fully  expressed, 
since  in  each  case  there  are  numbers  of  cells  which  are  not  zonal 
in  their  distribution,  but  which  conform  to  the  law  applicable  to 
Thujopsis  and  Podocarpus.    In  Juniperus  the  cells  are  typically 
zonate,  being  also  scattering  in  only  one  species.    In  Abies  only 
63.6  per  cent  of  the  species  bear  resin  cells.    These  are  neither 
scattering  nor  zonate  in  the  sense  of  the  previous  types,  but  it 
is  to  be  observed  that  in  50  per  cent  of  such  cases,  or  in  36.3 
^  per  cent  of  all  species,  they  are  aggregated  in  groups  as  a  pre- 
liminary step  to  the  formation  of  resin  passages.    On  the  other 
hand,  36.3  per  cent  of  all  species  show  the  resin  cells  to  be  few, 
inconspicuous,  nonresinous,  and  scattered  along  the  outer  face 
of  the  summer  wood.    This,  for  reasons  which  will  appear  more 
fully  later,  is  to  be  regarded  as  a  phase  in  distribution  leading 
to  the  final  obliteration  of  such  structures,  which  is  fully  accom- 
plished in  36.4  per  cent  of  all  the  species  as  represented  by 
A.  balsamea,  A.  Fraseri,  A.  lasiocarpa,  A.  Veitchii.    This  last 
form  of  distribution  is  wholly  typical  of  Tsuga  (plate  44),  in 
which  there  are  no  other  resin  cells  than  those  on  the  outer 
face  of  the  summer  wood.    Finally,  in  Picea  and  Pinus  there  are 
no  separate  resin  cells  in  any  of  the  situations  described,  since 
they  have  been  completely  replaced  by  highly  organized  resin 
passages.    It  thus  appears  that  the  distribution  of  the  resin  cells 
presents  four  variants  which  bear  a  direct  relation  to  the  organi- 
zation of  resin  passages,  as  the  latter  eventually  replace  the 
former.    These  facts  will  appear  somewhat  more  clearly  from  the 
summary  in  the  table  on  opposite  page. 

p-rom  such  data  it  is  clear  that  the  distribution  of  the  resin 
cells  bears  an  important  relation  to  the  recognition  of  subgeneric 
groups  and  even  of  species.  But  viewing  these  structures  from 
the  broader  standpoint  of  the  Coniferales  as  a  whole,  it  is  obvious 
that  they  must  be  placed  anion-,^  the  structural  elements  which 
belong  to  the  first  rank  for  ta.xonomic  purposes. 

We  are  now  in  a  position  to  determine  what  relation,  if  any, 
such  resin-bearing  elements  bear  to  questions  of  phylogeny, 
and  we  may  first  of  all  consider  the  resinous  tracheids.    These 


RESIN  CFAAJS 
Percentage  Distkibition  ok  Rksin  Cells 


119 


NiMBRK 

OH  Shecce 

Pkk  IKNTo 

'  j     .SlATTEK- 

1  t)N   THE  OlTBu 

■>     (KH'KKENCl 

ISG 

In  Zones 

(■KiUl'EnI       Fa<E(if.Si-m. 

MEK  WlKlU 

Gingko    .     . 

r 

1      ri-ic.iic 

Dammara     . 

j      ooo.co 

Araucaria     . 

1 

i      000.0c 

( 

'lorreya   .     . 

;       Ooo.r,ri 

Taxus      .     . 

4 

r.K.-.o 

Thujopsis     . 

I 

100.00 

100.00 

Crj'ptomeria 

I 

100.00 

100.00 

J'odocarpus . 

I 

100.00 

100.00 

(100.00) 

1  huya      .     . 

2 

66.600 

»=3 

1 00.00 

33-30 

I 

(33-30) 

Sequoia    .     . 

2  :=  2 

100.00 

100.00 

Cupressus    . 

I 

7 
5  =  9 

1 
I 

100.00 

53-90 

38.40 

50.00 

Taxodium    . 

100.00 

(100.00) 

100.00 

7.70 

I.ihocedrus  . 

I 

100.00 

(100.00) 

100.00 

Juniperus     . 

11  =  11 
I 

100.00 

1. 10 

100.00 

Abies  .     .     . 

4  =  7 

100.00 

36.30 

S 

2  =  5 

5 

'J'suga      .     . 

100.00 

45-50 
33-30 

I'seiidotsuga 

100.00 

100.00 

Liirix  .     .     . 

100.00 

4 

1 00.00 

I'iita  .     .     . 

10 

000.00 

100.00 

I'inus  .     .     . 

1 

41 

000.00 

structures  have  been  seen  to  be  peculiar  to  Dammara,  Araucaria 
and  Ab.es.  m  which  they  occur  only  in  certain  species.  In  answer- 
ing this  question  we  cannot  avail  ourselves  of  evidence  derived 
from  fossil  plants,  since  it  is,  in  such  cases,  of  a  negative  char- 
actor.  Neither  Cordaites  nor  Araucarioxylon  affords  definite 
proof  of  the  presence  or  absence  of  such  structures,  since  they  do 
not  appear  in  any  of  the  published  diagnoses,  and  our  own  studies 
have  not  resulted  in  their  recognition.    If  originally  present,  they 


'in 


120 


ANATOMY  OF  THE  OYMNOSPERMS 


must  have  been  obliterated  in  the  course  of  fossilization.  We 
must  therefore  depend  entirely  upon  such  evidence  as  is  afforded 
by  existing  species.  From  this  point  of  view  it  is  obvious  that 
they  furnish  no  evidence  as  to  the  origin  of  either  of  the  three 
genera  in  which  they  occur.  It  is,  on  the  other  hand,  possible  to 
determine  from  other  data  that  both  Dammaraand  Araucaria  are 
much  inferior  to  Abies  in  point  of  structural  organization  and 
development,  and  from  this  we  may  be  permitted  to  conclude 
that  the  resin  tracheids  of  Abies  are  vestigial  forms  of  elements 
which  were  typically  developed  in  Dammara  and  Araucaria,  and 
possibly  characteristic  also  of  their  progenitors.  If  such  infer- 
ences are  to  be  regarded  as  justifiable,  they  go  far  to  support 
the  idea  of  a  common  origin  for  all  three  genera,  and  they  thus 
lend  force  to  conclusions  which  lead  to  the  same  result,  but 
upon  the  basis  of  independent  data. 

From  a  study  of  the  distribution  of  the  resin  cells  it  is  appar- 
ent that  they  fall  into  four  categories  in  which  the  typically 
segregated  cells  may  be  hjld  to  represent  the  most  primitive 
form  of  disposition.  This  view  is  greatly  strengthened  by  the 
observation  that  in  all  such  cases  the  resin  cells  are  rarely  if  at 
all  accompanied  by  parenchyma  tracheids,  while  the  structure  of 
the  cell  is  farthest  removed  from  that  which  is  found  to  enter 
into  the  composition  of  resin  passages,  whence  they  are  also  to 
be  regarded  as  of  a  primitive  character.  This  view  is  supported 
by  the  observed  fact  that  those  genera  and  species  in  which  such 
segregations  occur  are  also  of  a  relatively  primitive  type.  With 
an  advance  in  organization,  there  is  a  tendency  to  the  formation 
of  aggregates  as  expressed  in  the  zonal  distribution  of  Taxodium, 
Libocedrus,  or  Sequoia,  where  we  also  find  the  definite  forma- 
tion of  groups  of  cells  which  later  exhibit  the  initial  stages  in 
the  formation  of  a  definite  canal.  But  in  Sequoia,  as  also  in 
Abies  where  similar  changes  take  place,  the  more  complete  aggre- 
gation of  the  cells  is  invariably  accompanied  by  structural  altera- 
tions whereby  they  become  greatly  shortened  and  more  strongly 
pitted,  while  they  are  always  accompanied  by  parenchyma  tra- 
cheids with  which  they  are  interchangeable.    In  this  connection 


RESIN  CELLS 

121 

posed.,  a  -.Cnt;::Cabtr.HT:;::r;^^^^^ 

of  the  separate  elements,  -a  relation  whL-  T  ^'^P°^'*'°" 
with  the  view  already  advanced  that  t^  ".  'H  '""'  ''""°"y 
isolated  cells  is  an  advance  uo^ntL.  ,  ''''P^'"'^"  °^  ^^« 
and  that  it  leads  directly  to  th.  f  '  "'^'^''^  ^''^™' 

Following  upon  the  :onJl  ^s^^nT::^^^,  ''''''''■ 
gation  results  in  the  formation  nfi      ^  """^^^^^  ^^^rt- 

ce,u  „,.„a.e„  .«.4 Tt' vis  r';^'  ::::^ 

zonal,  and  grouped  forms  bear  such  relation,  .1      '"^"'""K. 

«...  s.  »"^*e:itri:rrj':^::t:-To"r'"^ 

groups  and  eventually  imperfectly  organi  J^Stnl  "™ 
in  Cupressus,  the  transition  is  expressed  In  =         '=^'^"  ■  ■>'. 
<»™,  involving  all  three  modes  oTStir  iTts  "Th^^ 
IS  an  obvious  tendency  toward  the  elimination  of  ,L  re  *^  1'  ,s 
«:  r  ^^"'^  ^'"""O  '"  """■^-  --  con«S  tolS 

K=sin"i,:arU;:s-t\hirfr«fr-r::i 

^pcAs    This  r        *""'""'™  P'"=«e<l  in  the  same 

species.    This  IS  mdlrectconformitywith  the  idea  IWH,. 
passage  eventuallv  displaces  the  resin  cell    hr,?  J  " 

obliteration  of  the  latter  ,nH  ;,  ,  '  ""'"einK  about  an 

-3..ote^'-;t^:rerth:rj^;j£'or 


122 


ANATOMY  OF  THE  GYMNOSPERMS 


Furthermore,  from  another  point  of  view,  the  gradual  replace- 
ment of  the  resin  cells  appears  to  be  indicated  by  a  correspond- 
ing reduction  in  the  contained  resin.  Nowhere  is  the  resin  so 
abundant  in  the  resin  cells  as  in  those  genera  like  Podocarpus 
and  Taxodium,  which  show  no  development  of  resin  passages, 
even  in  their  most  simple  forms ;  but  with  the  development  of 
resin  sacs,  as  in  Abies  or  Sequoia,  or  of  resin  passages,  as  in 
Larix  and  Pseudotsuga,  there  is  a  remarkable  diminution  of  the 
resin,  apparently  in  direct  response  to  its  more  ready  production 
by  more  specialized  structures. 

The  genus  Abies,  then,  appears  to  form  a  transition  group, 
having  parallelisms  with  Dammara  and  Araucaria  through  the 
occurrence  of  resin  tracheids ;  with  Thuya,  Cupressus,  etc., 
through  the  survival  of  is'  d  resin  cells  approaching  oblit- 
eration ;  with  Tsuga,  Larix,  anu  «  otsuga  through  the  devel- 
opment of  rudimentary  resin  canals  leading  to  the  formation  of 
definite  resin  passages ;  and  with  Sequoia  through  the  survival 
of  isolated  resin  cells  and  the  development  of  rudimentary  resin 
canals.  Through  these  parallelisms  the  connection  appears  to 
be  most  direct  with  Sequoia,  on  the  one  hand,  and  with  Tsuga, 
on  the  other.  This  relation  of  Sequoia  to  Abies  has  been  shown 
by  Penhallow  on  former  occasions  (59),  and  has  more  recently 
been  indicated  in  other  ways  by  Jeffreys  (24) ;  but  so  far  as  the 
present  evidence  is  of  value  it  would  not  permit  us  to  infer  that 
Sequoia,  Abies,  and  Tsuga  form  a  continuous  and  conterminous 
series  in  the  order  given,  but  rather  that  they  represent  sepa- 
rate, though  short,  side  lines  of  development,  between  which 
the  general  sequence  is  manifested. 


CHAPTER   IX 


f; 


RESIN  PASSAGES 

Structural 

Our  studies  of  the  resin  cell  have  shown  how  peculiar  aggre- 
gates of  these  structures  lead  in  a  natural  way  to  the  organiza- 
tion of  resm  passages,  the  structure  of  which  it  is  now  necessary 
to  discuss  somewhat  in  detail,  and  in  doing  so  it  will  be  most 
profitable  to  have  reference  to  (i)  the  primitive  form,  (2)  the 
.ntcrmediate  form,  and  (3)  the  advanced  or  fully  organized  form 
The  primitive  form  .f  the  resin  passage  is  to  be  found  in 
i  suga.  Abies,  and  Sequoia,  and  inasmuch  as  within  these  genera 
they  exhib-c  differences  in  organization  which  correspond  approxi- 
mately to  the  sequence  given,  it  will  be  necessary  to  discuss 
them  somewhat  in  detail,  with  special  reference,   however,  to 
Sequoia.    This  genus  possesses  special  interest  with  respect  to 
the  occurrence  and  organization  of  secretory  reservoirs,  since  it 
IS  in  all  probability  not  only  the  most  ancient  genus  in  which 
such  structures  occur,  but  it  is,  so  far  as  I  am  aware,  the  only 
genus  affording  special  data  with  respect  to  important  varia- 
tions of  structure  and  mode  of  occurrence.    Being  also,  on  the 
whole,  the  most  primitive  of  the  three  genera,  it  may  be  dealt 
with  first. 

In  Sequoia  sempervirens  the  secretory  reservoirs  occur  in 
rows  within  the  initial  layers  of  the  spring  wood,"  and  they 
therefore  lie  exactly  on  the  outer  face  of  the  summer  wood  of 
the  previous  year.  Within  this  row  the  reservoirs  are  contigu- 
ous, and  in  many  cases  they  become  confluent  so  as  to  form  a 

»  The  apparent  occurrence  of  these  structures  in  the  summer  wood  is  due  to  the 
presence  of  two  growth  rings  of  very  unequal  degree  of  development,  the  outermost 
"1  v^h.ch  may  have  only  one  or  two  rows  of  tracheids  in  addition  to  the  resin  cysts. 

'23 


>ii 


124 


ANATOMY  OF  THE  C.YMNOSPERMS 


more  or  less  extended  and  continuous  compound  reservoir,  lying 
tangential!)-.  In  their  most  rudimentary  forms  they  present  the 
aspect  of  simple  aggregates  of  resin  cells  without  any  differen- 
tiation of  a  resin  sac  or  of  an  epithelium.  In  a  more  advan  :ed 
stage  of  development  there  is  produced  a  central  cavity  in  the 
form  of  an  intercellular  space  (fig.  38,  C)  which  has  obviously 
originated  schizogenously.  About  this  the  resin  cells  are  gen- 
erally flattened  radially  and  disposed  in  such  a  manner  as  to 
suggest  the  future  development  of  a  definite,  limiting  layer  or 

epithelium.    In  the 
MR.        r~\V    (k.  completed  form  of  the 

structure  the  central 
space  has  broadened 
out  and  taken  a  cir- 
cular form,  assuming 
the  character  of  a  defi- 
nite cyst  bounded  by 
as  definite  a  limiting 
epithelium  in  which 
the  cells  are  always 
flattened  radially  and 
disposed  concentric- 
ally (fig.  38,  Q.  E.x- 
ternally  to  these  cells 
there  may  be  a  second 
layer  of  similar  resin 
cells,  constituting  the  outer  epithelium,  while  the  whole  is  inclosed 
on  three  sides  by  a  layer  of  parenchyma  tracheids  which  arc 
exceedingly  like  the  associated  tracheids  of  the  spring  wood,  but 
from  which  they  may  usually  be  distinguished  by  (i)  their  greater 
size  and  relatively  thinner  walls,  and  (2)  the  occurrence  of  bor- 
dered pits  on  the  tangential  and  terminal  as  well  as  upon  the 
radial  walls.  Such  parenchyma  tracheids  never  occur  in  the  adja- 
cent summer  wood  for  very  obvious  reasons,  but  on  the  radially 
opposite  side  of  the  reservoir  they  are  very  commonly  flattened 
radially  (fig.  39),  and  they  not  infrequently  present  the  same 


■■■sw 


Fig.  38.  Sequoia  sempervirens.  Transverse  sec- 
tion showing  two  contiguous  resin  cysts  :  C,  com- 
pleted and  with  a  normal  epithelium  {E.) ;  C.\  an 
intercellular  space  as  the  rudiment  of  a  cyst  with 
imperfectly  developed  epithelium ;  M.K.,  the 
medullary  ray  ;  S.  IV.,  the  summer  wood,     x  225 


RESIN  lASSAGKS 


"5 


structural  aspects  as  the  epithelial  cells.  The  interchanirpnhin 
relafon  between  resin  cell  and  parenchyma  trLhe^as  Cd^^^ 
shown  would  lead  us  to  suspect  a  substitution  in  the  con^pos  t  oi 
of  the  epthehum,  and  such  substitution  does  actually  occur  Tee 
.  IS  often  to  be  noted  that  the  second  and  third  rows  iTbe 
made  up,  at  least  in  part,  of  tracheids  ^ 

thJ?ol!T''"'''"?'  "''''  '''^'""  ^'^^  '■^^^"'"•^  •«  f«"'«>  to  have 
theformofasacof  vary  ^g  form  and  size,  but  generally  elongated 


which  contains    "in  l^do;  1  l^rct      "  ^T'^i  '"^  "'^'"^^•■'  <'^')-  ""^  "' 
cell;  the  parenchyma  (/no     x  3^  '  """"'  ''"""  ^"  ^'^'"''^"""' 

cndf  lto^''T^"  ^'v,^"'''  ^"'  ^^'"•^'^^^^y  ^^«-^  ^^  both 
limi  s^of'th?"  '^"n'''"'"'  "'''^'  i'^'^ediatcly  defines  the 

gated  bang  several  tm.es  longer  than  broad.    Beyond  this,  the 

be  when'  """T      P^'-^"^^^"'^  t-^heids,  readily  distinguish- 

ble  whenever  the  terminal  walls  lie  near  the  plane  of  section,  or 

herw.se  recogmzable,  as  already  indicated.    Certain  deviati;ns 

trum  this  typical  structure  require  examination.    The  resin  sacs 


!  lit  i 


126 


ANATOMY  OF  THE  GYMNOSPERMS 


arc  p' 

intei 

onl; 

the 

tra 


^MT 


'd  in  vertical  series  of  indeterminate  extent,  but  at  varying 

(if  such  a  nature  that  they  may  sometimes  be  separated 

a  rather  thick  wall  of  shori  resin  cells.    At  other  times 

J  somewhat  distant  and  separated  by  an  extensive  vertical 

jf  resin  cells.    From  this  it  is  obvious  that  in  any  given 

plane  of  section  then 

will  be  a  great  diversity 

/   Tv  \  \\      ^^  of  aspects  presented,  but 

I     y%--fA  \J)p^q    C^         in  the  main  exhibitinj; 

IL^( />»  \>  r-\\  \^^~^    structural   gradations   in 

the  development  of  the 
reservoir,  as  already  re- 
counted.   In  some  cases 
thick-walled  cells  of  cir- 
cular outline  may  be  seen 
in  transverse  section  to 
stand  out  from  the  [;en- 
eral  line  of  the  epithelium 
and  lie  within  the  cavity 
proper.   More  rarely  such 
cells  are  so  multiplied  as 
to  fill  the  entire  cavity, 
and  they  may  themselves 
be  filled  with  granular 
resin.    Such  features  arc 
clearly  defined  (fig.  39), 
and  it  is  evident  from  the 
way  in  which  such  cells 
originate  from  the  epithe- 
lial cells  that  they  are  of 
the  nature  of  thyloses.    A  longitudinal  section  through  such  a 
reservoir  (fig.  41)  shows  how  such  thyloses  occupy  the  entire 
cavity  of  the  cyst,  while  in  other  cases  they  may  be  purely  local 
/fig.  40).    Among  fossil  Sequoias  similar  thyloses  form  a  most 
characteristic  feature  in  the  resin  passages  of  the  medullary  rays 
in  S.  Burgessii  and  S.  Penhallowii. 


Fig.  40.  .Sequoia  SF.MPERViRENs.  Radia' sec- 
tion of  a  resin  cyst  sliowing  the  epithelium 
(£•/.) ;  the  central  cyst  (r.)  with  a  thylosis  (t/i.) ; 
parenchyma  tracheitis  (/•r.t.),  and  a  tracheid 
of  the  lipring  wood  {Sp.  T.).    x  300 


RKSIN   PASSAGES 


III 


127 


^P 


In  Tsuga  caroliniana  there  are  no  secretory  reservoirs    but 
just  in  the  regioi.  between  the  spring  and  summer  wood  of  the 
same  growth  ring  there  are  pccuhar 
aggregates  of  resin  cells  of  a  more 
or  less  rounded  outline,  forming  a 
continuous  series  of  considerable 
extent.    An  analysis  of  these  aggre- 
gates shows  them  to  be  comjwsed  of 
thick-walled  and  rounded  resin  cells, 
among  which  there  may  be  a  small 
central,  intercellular  space  without 
any  definite  organization  of  epithe- 
lium.   In  such  aggregates  the  com- 
ponent cells  are  far  less  resinous 
than  the  isolated  re.sin  cells  of  the 
same  section.    The  parenchyma  tra-   f/>. 
cheids  are  not  clearly  distinguishable 
from  the  associated  wood  tracheids. 
In  radial  section  the  cells  are  seen 
to  be  very  variable,  thick-walled,  and 
-sometimes  with  more  or  less  promi- 
nent intercellular  spaces.    Between 
the  rays  they  are  several  times  longer 
than  broad,  but  opposite  the  rays 
they  are  short,  cylind    jal,  and  more 
copiously  pitted ;  while  sometimes 
they  may  be  se.     to  merge  into  ray 
elements  and  thus  to  continue  their 
course  at  right  angles  to  their  pri- 
mary direction.    A  careful  compari-  F„;.4,.  .sk-,,    .a  .sKMr,.Kv,K.Ns. 
son   of  these   cell  aggregates   with      '**'^''*'  ''''    ""  "f  a  f'^'^in  lyst 
those  of  Sequoia  and  Abies  leivcs      '*';"«'"'?""- epithwium (<•/.)  and 

llttle  room  for  doubt  as  to  their  StrilC-        P'«^tely  fill  the  cyst,  and  .several 

tural  and  .'jnctional  identity,  and  we      "^  "'""'' '"'''  ''-■■*'"»"'*•    ^  "5 
cannot  do  otherwise  than  conclude  that  they  represent  the  most 
primitive  structural  condition  which  is  capable  of  directly  giving 


h 
\ 


138 


ANATOMY  OF  THE  G.MNOSPERMS 


rise  to  definite  cysts  by  central  cleavage,  and  that  such  cysts 
are  precedent  to  the  formation  of  canals. 

In  Tsuga  Mertensiana  the  secretory  reservoirs  are  disposed 
like  those  of  Sequoia,  on  the  outer  face  of  the  summer  wood, 
where  ^hey  form  tangential  scries.  They  exhibit  all  the  grada' 
tions  from  simple  cell  aggregates  without  a  central  space  to  per- 
fectly formed  cysts  with  a  definite  epithelium.  This  latter  is  in 
one,  more  rarely  in  two,  rows,  and  it  is  composed  of  more  or  less 
rounded  or  radially  flattened  elements.  The  parenchyma  tracheids 
are  few  in  number,  and  they  are  not  readily  distinguishable  from 
the  adjacent  wood  tracheids.  In  longitudinal  section  the  reser- 
voirs  are  variously  rounded  or  oblong  cysts,  contiguous  or  isolated 
and  forming  a  longitudinal  series.  In  their  general  form  and 
structure  they  are  essentially  the  same  as  in  Sequoia. 

In  the  genus  Abies  secretory  reservoirs  occur  in  at  least  tour 
species,  where  they  form  more  or  less  extensive  tangential  series, 
within  which  they  are  usually  contiguous  and  more  or  less  con- 
fluent.   They  present  the  same  general  variations  in  structural 
organization  as  in  Tsuga  and  Sequoia,  but  in  A.  concolor,  and 
less  cnspicuously  in  A.  nobilis,  they  are  often  extended  in  a 
radnl  ,'nr,  :tion  so  as  to  become  narrowly  oval  or  oblong  and 
several  times  longer  than  broad.    The  epithelium  consists  of  a 
well-defined  structure  composed  of  from  one  to  three  rows  of  cells. 
The  first  row,  immediately  bt^rdenng  upon  the  canal,  consists  of 
rounded  or  oval  and  thick-walled  cells,  which  are  much  smaller 
than  those  of  Sequoia  and  similar  to  those  of  Tsuga.    They  arc- 
always  characterized  by  an  abundance  of  strongly  defined,  simple- 
pits,  and  many  of  them  contain  resin,  which  usually  takes  the 
form  of  rounded   granules  of  diverse  sizes.    The  parenchyma 
tracheids  are  so  nearly  like  the  accompanying  wood  tracheids  as, 
m  some  cases,  to  be  separable  with  some  difficulty,  but  they  gen- 
erally surround  the  resin  sac,  at  least  within  the  limits  of  the 
spring  wood,  and  they  not  infrequently  replace  the  parenchyma 
cells  of  the  epitheHum  more  or  less  completely.    Not  infrequently 
they  form  somewhat  extended  radial  series  from  the  epithelium 
mto  the  spring  wood,  as  in  Picea  (fig.  43).    In  such  cases  they  are 


RKSm  PASSAGES  ,, 

■n  the  case  of  A  concolor,  in  which  species  they  al  essent  allv  If 
c*  m  .ho  Cher  f„rm,„g  a  ,is,„.  which  nearly  fflW  ,hc  .n.ije 

regions  or  Sequoia  and  Tsn,a  MerS^^^e ^he  1""' 
ff««  wh,ch  are  generally  eharactcristic  „f  Tsuga  JartlST 
The  .nner  epithelium  usually  consist,  of  short  c^'S  and 
strongly  pitted  cdls,  which  in  the  second  and  third  !T 

»e    hen  replaces  the  other.    The  parenchyma  trached.  1  Lh 
are  always  most  characteristic  of  the  spring  wood    ;„    , 
istingnished  by  the  presence  of  large  IdTrlSn'LS 

From  these  fact        is  clear  that  the  secretory  reservoirs  of 

Lcs  whTchTV"  r'?  ^'"">'  '"'<'  '"=  'oZo^'Z^ 
sacs,  „h,ch  De  Bary  has  already  pointed  out  a,  a  feature  of 


f-' 


130 


ANATOMY  OF  THK  C.YMNOSPERMS 


certain  Conifcrac  (18,  440),  and  in  order  to  clearly  differentiate 
them  from  those  which  occur  in  the  genus  Pinus  I  shall  reserve 
for  all  such  cases  the  term  resin  cyst.  While  such  cysts  arc 
typically  developed  in  the  three  genera  named,  they  are  also 
features  of  Pseudotsuga,  Larix,  and  Picea,  —  in  fact,  of  all  those 
genera  in  which  the  epithelium  is  composed  of  thick-walled  cells, 
—  but  in  these  latter  cases  there  is  the  additional  feature  that 
such  cysts  are  always  accompanied  by  the  occurrence  of  similar 
structures  in  the  medullary  rays,  and  therefore  they  are  asso- 
ciated with  fusiform  rays.  From  these  facts,  then,  it  is  obvious 
that  we  have  here  a  group  of  six  genera  all  characterized  by 
the  presence  of  structurally  similar  resin  reserve  rs,  but  scjia- 
rable  into  two  groups  through  the  absence,  on  the  one  hand, 
and  presence,  on  the  other,  of  fusiform  rays.  That  such  saclike 
reservoirs  represent  the  primitive  form  of  the  resin  passage 
scarcely  admits  of  question  when  we  observe  the  various  transi- 
tional forms  which  they  present,  and  the  relation  which  they  bear 
to  the  resin  passages  of  Pinus,  —  a  view  which  is  strengthened 
by  the  observation  of  De  Bary  (13,  443)  that  primitive  forms  of 
the  secretory  reservoir  occur  in  the  pith  of  Gingko  in  the  form 
of  elongated  sacs. 

De  Bary  has  shown  that  (13,  440)  the  secretory  passages 
traverse  the  wood  longitudinally,  at  first  as  prismatic  tubes, 
which  usually  acquire  a  round  or  elliptical  transverse  section.  In 
its  strict  sense,  this  statement  is  applicable  exclusively  to  the 
genus  Pinus,  but  inasmuch  as  there  are  important  structi'nl 
gradations  whereby  Pseudotsuga,  Larix,  and  Picea  represent  un 
intermediate  type,  while  Pinus  represents  a  completed  type,  it 
will  be  necessary  to  compare  them  somewhat  in  detail.  In  the 
genus  Pinus,  however,  the  secretory  reservoir  differs  from  that 
of  all  other  genera,  in  that  it  consists  of  a  definite  and  continu- 
ous canal  of  indeterminate  length,  and  for  the  purpose  of  differ- 
entiating it  from  other  forms  I  shall  reserve  for  it  the  appropriate 
and  long-used  term  resin  f  is  sage. 

In  Pseudotsuga  the  resin  cy.sts  are  always  scattering,  though 
they  frequently  occur  in  tangentially  extended  groups  of  two  or 


RKSIN   PASSAG^:S 


«3I 


four  contiguous  or  even  coalesccnt  reservoirs.    The  central  canal. 
which  is  usually  small  anil  not  infrequently  very  narrow,  is  rather 
more  generally  rounded  than  in  previous  types.    The  epithe- 
lium is  very  clearly  defined  and  consists  of  opt-  to  three  rows  of 
thick- walled  parenchyma  cells,  sometimes  containing  resin,  the 
first  row  of  which  are  rather  small  and  radially  flattened,  but 
in  P.  macrocarpa  they  arc  rather  thin-walled.    In  P.  DouKlasii 
the  epithelium  is  commonly  extended  on  the  two  sides  of  the 
resin  canal  in  such  a  way  as  to  form  a  tangentially  elongated 
tract  which  not  infrequently  extends  beyond  and  involves  neigh- 
boring  medullary  rays.    In  P.  macrocaqKi,  on  the  other  hand, 
the  epithelium   is  concentric  with  the  canal,   thus   forming  a 
tract  of  aljout  equal  thickness  all  around.    Such  a  deviation  as 
is  expressed  in  P.  Douglasii  constitutes  the  first  evidence  of  a 
tendency  in  development  which  is  fully  and  frequently  expressed 
in  Pinus.    Thyloses  are  of  infrequent  occurrence,   and  apjx:ar 
to  be  confined  to  P.  macrocari)a  where  they  are  few  in  number 
and  generally   rather   thin-walled.    Parenchyma   tracheids  are 
usually  not  apparent  in  a  transverse  section.    This  results  from 
the  frequent  IcK-ation  of  the  resin  passage  in  the  summer  wood, 
which  is  not  favorable  to  their  development,  and  from  the  close 
resemblance  which  they  bear  to  the  tracheids  of  the  spring  wood  ; 
and  while  such  elements  form  an  integral  part  of  the  resin  cyst, 
their  particular  disposition  cannot  be  exactly  defined,  though 
there  is  no  good  reason  for  supposing  that  they  differ  in  this 
respect  from  what  may  be  observed  in  other  cases.    In  a  longi- 
tudinal section  the  canal  is  found  to  be  more  or  le.ss  continuous, 
though  it  presents  frecjuent  constrictions  and  is  thereby  reduced 
to  very  narrow  dimensions,  or  it  may  even  be  discontinuous  and 
thereby  form  cysts.    It  is  this  feature  which  causes  the  canal  to 
exhibit  such  marked  variations  in  size,  when  seen  in  transverse 
section.    The  epithelial  cells  are  narrowly  cylindrical  and  rather 
limg  and  thick- walled,  as  well  as  somewhat  strongly  pitted.    Out- 
wardly they  become  much  longer  and  relatively  narrower,  and 
they  eventually  merge  with  the  surrounding  {^renchyma  tra- 
cheids, by  which  they  may  also  be  replaced  (fig.  42). 


1 


#i 


132 


ANATOMY  OF  THE  GYMNOSPERMS 


In  Larix  the  same  features  of  contiguity  and  coalescence  may 
be  observed,  except  that  in  L.  occidentalis  the  resin  passages 
sometimes  form  into  continuous  zones  of  imperfectly  organized 
structures  with  the  aspect  presented  in  Tsuga  Mertensiana.  The 
epithelium  is  always  well  defined  (fig.  42),  and  it  consists  of 
one,  sometimes  two,  rows  of  cells.    The  cells  of  the  first  row  are 

small,  very  variable  in  form  and 
size,  thick-walled,  and  more  or 
less  strongly  flattened  radially. 
They  are  also  commonly  resin- 
ous and  more  or  less  strongly 
pitted.    When  there  is  a  sec- 
ond row  of  epithelium  the  ceils 
are  essentially  like  the  wood 
tracheids,  and  like  the  paren- 
chyma tracheids,  from  whicli 
they  may  be   separated  witli 
difficulty.    The  latter,  there- 
fore, which  are  absent  from  the 
summer  wood,  can  be  distin- 
guished from  the  elements  of 
the  spring  wood  only  when 
the  pits  on  the  terminal  walls 
(fig.  42,/r.A)  are  brought  into 
view,  or,  more  rarely,  when  the 
pits  on  the  tangential  walls  are 
in  evidence.     Thyloses  rarely 
occur,  and  so  far  they  have  been 
noted  only  in  L.  occidentalis. 
where  they  are  infrequent  and  thick-walled,  and  in  L.  americana, 
where  they  are  of  rare  occurrence  and  thin-walled.    In  longitu- 
dinal section  the  central  canal  is  always  continuous,  though  con- 
stricted at  intervals,  a  feature  in  all  essential  respects  the  same 
as  in  Pseudotsuga.    Radially  the  first  row  of  epithelial  cells  art- 
short  cylindrical,  or  in  L.  occidentalis  short  fusiform,  but  there  i< 
a  graduated  increase  in  length  outwardly,  so  that  in  the  second 


sza 


Fig.  42.  Larix  occidentalis.  Trans- 
verse section  from  the  inner  spring 
wood  sliowing  a  pair  of  resin  passages 
with  the  central  canals  (c.) ;  the  thick- 
walled  epithelium  (<•/.) ;  a  parenchyma 
tracheid  (frj.),  and  the  summer  wood 
(s.w.).    X  300 


RESIN  PASSAGES 


133 


row.  or  m  the  third  if  present,  they  become  narrow  and  very 
long,  and  they  eventually  blend  with  the  parenchyma  tracheids 
through  intermediate  forms  with  bordered  pits.  All  of  the  epithe- 
lial cells  are  thick-walled  and  strongly  pitted,  and  they  thus  offer 
a  somewhat  strong  contrast  to  the  rather  thin-walled  parenchyma 
tracheids  with  bordered  pits. 

The  resin  passages  of  Picea  differ  from  those  of  Pseudotsuga 
and  Larix  in  being  more 
strictly  segregated,  and  in 
consequence  there  is  a  con- 
spicuous absence  of  contig- 
uous structures,  which  may 
nevertheless  sometimes  be  P^^'. 
seen  in  P.  nigra,  and  espe- 
cially of  coalescent  forms. 
They  are  usually  narrow, 
but  well  rounded  or  oval, 
and  there  is  far  greater  uni- 
formity of  structure  and 
form  than  in  any  of  the  pre- 
ceding types.    The  epithe- 
lium consists  of  one  row, 
one  to  two  rows,  or  even 
one  to  three  rows  of  cells, — 
differences  which  appar- 
ently belong  to  particular 
species,  though  no  attempt 
has  been   made  to  define 
the  precise   limitations  of 

such  features.  The  cells  are  generally  small,  round,  or  radially 
flattened  and  thick-walled,  though  occasionally  a  cell  may  be 
'hm-walled,  as  in  P.  alba.  In  cases  of  thick-walled  epithelium 
the  outermost  cells  merge  with  similar  tracheids,  from  which 
they  are  not  readily  distinguishable,  while  the  general  epithelium 
becomes  extended  into  a  tangentially  elongated  tract,  as  in  Pseu- 
Uotsuga  Douglasii  and  Pinus.    Occasionally  thyloses  have  been 


Fig.  43.  Picea  alba.  Transverse  section  of 
a  resin  passage  from  the  spring  «  ood  show- 
ing the  central  canal  (c);  the  thick-walled 
epithelium  (ep.),  and  the  parenchyma  tra- 
cheids (pr.t.).    X  300 


i  &-• 


*]■ 


iv. 


»34 


ANATOMY  OF  THE  GYMNOSPERMS 


noted  in  P.  nigra,  P.  pungcns,  and  P.  sitchensis,  but  they  are 
always  thin-walled.  Parenchyma  tracheids  are  not  obvious  in 
the  summer  wood,  but  they  are  recognizable  in  the  spring  wood, 
where  they  appear  to  replace  the  resin  cells,  though  they  are 
apparently  of  much  less  frequent  occurrence  than  in  the  genera 
previously  discussed.  In  P.  alba,  however  (fig.  43,  prJ.),  we 
sometimes  find  a  radial  series  of  tracheids  which  also  extends 
laterally  so  as  to  form  an  inclosing  layer.  Longitudinally  the 
canal  is  continuous,  but  with  more  or  less  frequent  constrictions, 
as  in  Pseudotsuga  and  Larix.  The  epithelium  consists  of  narrow 
cylindrical  and  much-pitted  cells,  which  increase  in  length  in  the 
outer  layers,  where  they  become  five  to  seven  times  longer  than 
broad,  and  finally  merge  with  the  parenchyma  tracheids,  which 
replace  them. 

While  the  general  composition  of  the  resin  passage  in  Pseu- 
dotsuga, Larix,  and  Picea  is  the  same  as  that  of  the  resin  cyst, 
it  is  obvious  that  the  frequent  constrictions  in  the  canal  indicate 
a  partial  survival  of  the  cystic  formation.  We  must,  therefore, 
regard  these  structures  and  the  three  genera  to  which  they 
belong  as  forming  a  transition  group  between  the  primitive 
resin  cyst,  on  the  one  hand,  and  the  perfectly  organized  resin 
passage  of  Pinus,  with  its  canal  of  uniform  width,  on  the  other. 

In  the  genus  Pinus  the  resin  passages  show  considerable  vari- 
ation in  detail,  but  they  all  conform  to  the  same  structural  tyj^e 
(fig.  44).  The  central  canal  is  broad  and  round,  often  very  large, 
and  in  longitudinal  section  it  is  a  perfectly  continuous  passage 
of  uniform  width.  The  epithelium  consists  of  large  but  very  vari- 
able and  thin-walled  cells  in  from  one  to  several  rows.  In  the  soft 
pines  it  generally  forms  a  concentric  zone  of  uniform  width,  but 
in  several  of  the  hard  pines  there  is  a  marked  tendency  to  exten- 
sion in  a  tangential  direction  and  the  formation  of  rather  exten- 
sive eccentric  tracts.  In  all  of  the  pines  there  is  a  pronounced 
tendency  for  the  epithelial  elements  to  become  so  thin-walled 
that  they  are  readily  broken  out  in  making  sections,  while  in 
the  hard  pines,  as  P.  cubensis,  P.  tneda,  P.  pungens,  etc.,  the 
cells  are  often  strongly  resinous.    In  the  outer  epithelium  the 


RESIN  PASSAGES 


H 


•oj 


thm-walled  elements  may  be  associated  with  occasional  thick 
walled  elements  with  which  th  ,  are  interchangeable,  precisely 
as  m  the  similar  relations  displayed  by  the  medullary  rays  of 
P.  pungens  and  P.  cubensis.  In  the  same  region  also  there  is 
a  simdar  association  with  and  transformation  into  parenchyma 
tracheids.  which  also  has  its  parallel  in  the  medullary  ray.  Some- 
wliat  more  specifically,  special  reference  to  two  examples  may 


S.W- 


SM 


'iL.IfZ  «^^'«-^A  Transverse  section  of  a  resin  passage  from  the  inner 
re  inc  e„rr^  wood  showmg  the  central  canal  (C);  the  thin-walled  and 
rsr»-»and  .h  ^'■^■''   "'^P-^^^hyma  tracheids  (/.);   the  spring  wood 

(.">/.«.)  and  the  summer  wood  (S.ll\)    x  225 

serve  to  illustrate  the  general  nature  of  some  of  the  more  im- 
portant variations.  In  longitudinal  section  the  parenchyma  tra- 
cheids are  usually  of  much  greater  length  than  the  associated 
parenchyma  cells,  with  which  they  are  parallel  or  conterminous, 
and  they  occur  in  large  numbers  in  P.  Lambertiana.  In  P.  reflexa 
they  are  conterminous  with  parenchyma  cells,  which  they  finally 
succeed,  to  be  replaced  in  turn  by  thin-walled  wood  ttacheids. 
In  P.  Lambertiana  they  are  always  to  be  distinguished  by  the 


K^ 


136 


ANATOMY  OF  THE  GYMNOSPERMS 


:   i*  V;J   ' 


bordered  pits  on  the  radial,  tangential,  and  terminal  walls,  while 
in  P.  reflexa  they  are  characterized  by  the  large  number  of  bor- 
dered pits  on  the  radial  walls,  with  very  few  on  the  tangential 
walls.  In  the  former  situation  the  pits  are  much  smaller  than 
in  adjacent  wood  tracheids.  Together  with  adjacent  wood  tra- 
cheids  the  parenchyma  tracheids  may  be  more  or  less  involved 
in  bearing  resin  (P.  Lambertiana),  while  finally,  as  exhibited  in 
transverse  section,  their  numbers  may  be  so  large  that  they 
form  extensive  areas  about  the  resin  passage  (fig.  44).  In  such 
a  case  the  sequence  of  elements  in  transverse  section  would  be : 

1.  Canal  with  thyloses. 

2.  Thin-walled  epithelium. 

3.  Epithelium  and  cylindrical  parenchyma  tracheids. 

4.  Parenchyma  tracheids. 

5.  Wood  tracheids  with  thin  walls. 

Thyloses  are  a  constant  feature  in  the  structure  of  the  resin 
passages  of  Pinus  (fig.  31,  a).  They  are  always  thin-walled  and 
completely  fill  the  canal.  So  constant  are  these  features  in 
association  with  those  previously  recounted  that  they  serve  to 
afford  a  ready  means  of  accurately  recognizing  the  genus  under 
all  circumstances. 

The  general  course  of  development  thus  outlined  shows  that 
the  parenchyma  tracheid  stands  in  such  relation  to  the  organiza- 
tion of  the  resin  passage  that  its  more  frequent  occurrence  is 
directly  correlated  with  a  higher  type  of  organization  and  devel- 
opment in  the  plants  to  which  they  belong. 

We  are  now  in  a  position  to  present  a  general  summary  of 
the  relations  which  the  resin  cells  bear  to  the  organization  of 
the  secretory  reservoirs  —  csts  and  passages  —  and  the  position 
which  the  latter  occupy  in  the  economy  of  the  plant  as  follows : 

1.  Resin  cells,  which  are  of  the  nature  of  wood  parenchyma,  at  first  occur 

as  isolated  structures  filled  with  resin,  but  they  show  a  definite  tendency 
to  association  and  later  form  definite  aggregates. 

2.  Parenchyma  tracheids  become  associated  with  such  aggregates  for  the 

purpose  of  effecting  a  more  complete  nutrition  of  the  secretory  cells. 


RESIN  Passages 


^37 


central  canals  of  indeterminate  length  °""'^  '*''''  °'" 

a.  the  tracheids.  which  provide  nutrition  for  the  secret  ceirs 

"rSTeTpS."^  '"^'^"^  '"  *^'-  *^^  --"'of  the 

"  ''^?:r;L:^::;r'  ''^^''^^  ^"  ^-'^^^  °^  -^-^^  — ^  - 

-/.  the  thyloses,  which  may  impede  the  proper  storage  of  the  resin  or 
wh.ch  may  individually  serve  the  purpose  of  storage  ' 

in  te7S^  ""  I^'  ^°'''"'''°"  °^  '■^^•"  '^  "°^  «^«««ive  it  is  stored 
m  the  cells  where  produced.  This  is  true  of  all  isolated  reS 
cells  as  well  as  of  many  which  enter  into  the  composition  ^ 
complex  cysts  and  passages.    When  the  resin  is  excessTv     ho^ 

form  of  ,'"'.  ''  ''''■'^^'  '"^-^  ^P^^'^"^^^  r^e-oirs  c^f  the 
form  of  closed  cysts  or  of  canals,  and  we  are  led  to  interpret 
the  appearance  of  these  structures  in  the  higher  Conif  rL  aTl 

v.il  thus  be  seen  to  stand  in  direct  relation  to  the  capacTv  of 
the  plant  as  a  resin  producer,  -a  fact  which  is  otherZ  al/ 
ent  from  our  knowledge  of  the  general  capacity  of  the  diSm 

SthTi  r"  '"'"""'  ^"'  '^""^  ^  ^-P--"  of  this  ! 
with  theu:  known  position  in  the  line  of  descent. 


CHAPTER  X 

RESIN   PASSAGES  {continued) 
Distribution  and  Phylogenv 

Prantl  (62,  37)  states  that  resin  passages  occur  in  the  wood 
of  "most  Abietineae,  namely,  Pseudotsuga,  Picea,  Larix,  Pinus, 
and  Abies  firma."  This  statement  requires  some  modification 
in  detail,  especially  with  respect  to  the  last-named  genus,  and 
in  order  to  make  the  results  of  the  present  studies  clear  it  will 
be  expedient  to  discuss  separately  the  distribution  of  the  resin 
cysts  and  the  resin  passages. 

The  first  species  to  which  our  attention  may  be  directed  is 
Tsuga  Mertensiana.  This  is  the  only  species  of  the  genus  in 
which  definite  resin  cysts  are  to  be  found.  Such  structures  arc 
never  numerous,  and  they  take  the  form  of  short  rows  of  con- 
tiguous cysts  in  the  initial  layer  of  the  summer  wood  of  distant 
growth  rings.  Longitudinally  they  have  no  definite  limits,  but 
they  appear  to  be  extended  for  great  distances,  and  probably 
through  the  entire  longitudinal  growth  of  the  season,  at  least. 
There  is  no  obvious  alteration  either  in  the  position  or  volume 
of  the  resinous  contents  of  the  isolated  resin  cells  which  lie  on 
the  outer  face  of  the  summer  wood.  The  constancy  with  which 
these  structures  occur  gives  to  them  a  definite  value  for  the 
recognition  of  the  species,  and  permits  us  to  differentiate  it 
from  T.  caroliniana  on  the  one  hand,  and  from  the  remaininj,' 
three  species  on  the  other. 

In  the  genus  Abies  only  four  species  out  of  eleven  show- 
resin  cysts.  These  are  A.  bracteata,  A.  nobilis,  A.  concolor, 
and  A.  firma.  Referring  again  to  Prantl's  observation  (62,  37), 
it  must  be  pointed  out  that  his  statement  with  respect  to  the 
occurrence  of  resin  passages  in  A.  firma  requires  modification  in 

■38 


RESIN  PASSAGES 


'39 


detail  m  so  far  as  these  structures  are  not  passages  but  cysts ; 
wh.le  he  al8o  appears  to  have  overlooked  the  occurrence  of  simi- 
kr  structures  m  the  three  other  species  mentioned.  In  all  of 
these  cases  the  cysts  are  contiguous  and  disposed  in  tangential 
rows  of  considerable  length,  either  in  the  summer  wood  (A  con- 
co^r  and  A.  nobilis).  in  the  outer  spring  wood  (A.  firma);or  in 
both  the  spnng  and  summer  wood  (A.  bracteata).  Such  varia- 
.ons  appear  to  be  of  no  specific  value,  conforming  as  they  do 
to  similar  varmtions  in  the  zonate  distribution  of  the  rem  cells 

Lir^'  ^"""^'^''J^^'   •"  «"ly  one  case  (A.  concolor)  are 
these  cysts  associated  with  isolated  resin  cells.    In  the  three 

'^^  '':  "^'"  ""^  "^  '""'''^'y  -"ting.-a  relation 
uhich  IS  strongly  suggestive  of  their  replacement  by  the  cysts 

Sequoia  sempervirens  is  the  only  species  of  that  genus  which 
develops  resm  cysts  in  the  secondary  wood,  though  Jeffrey  (24) 
has  shown  that  such  structures  are  normal  to  the  primary  wood^ 
zone  of  S.  gigantca.  and  not  elsewhere.    As  already  shown,  such 
cysts  are  much  more  highly  organized  than  those  of  either  Tsuga 
or  Ab.es.  though  they  are  similarly  contiguous  and  even  ccS 
cscent,  and  form  ext-rnsive  tangential  rows  in  the  initial  layer  of 
the  spring  wood  of  d.  .ant  growth  rings.  They  form  a  much  more 
promment  feature  than  in  any  of  the  preceding  species  because 
of  their  generally  larger  size  and  the  greater  extent  of  the  serie! 
■n  which  they  lie.    Unlike  Abies,  however,  there  appears  to  be  no 
cl.minut.on  either  m  the  number  or  the  extent  of  The  prominent 
resm  cells,  wh.ch  are  often  intimately  associated  with  the  cysts 

The  normal  course  of  development  for  such  cysts  as  are  thus 
<lc.scnbed  IS  subject  to  special  alteration  under  conditions  which 
•nvolve  an  unusual  stimulus  to  growth,  and  under  such  circum- 
stances they  may  become  definitely  associated  with,  or  may 
even  be  regarded  as  indicative  of,  pathological  conditions.  Thus 
Anderson  (1,  28-29)  has  shown  that  such  cysts  are  definitely 
eveloped  m  association  with  the  formation  of  witches'  brooms 
m  Ab.es  firma.    Under  such  circumstances  the  cysts  become 

gro^vth.  but  they  form  well-defined  tangential  rows  in  the  eariier 


1 


140 


ANATOMY  OF  THF  GYMNOSPF.RMS 


spring  wood  of  successive  growth  rings.  In  the  development 
of  such  secondary  features  the  cysts  manifestly  e^'abit  a  dis- 
tinct approach  to  that  higher  type  of  structure  and  distribution 
which  is  exhibited  in  I'icea.  In  the  following  year  Anderson 
(2,  336)  further  showed  that,  while  resin  cysts  are  absent  from 
the  normal  wood  of  A.  balsamea,  they  do  arise  under  the  influ- 
ence of  the  special  stimulus  connected  with  the  formation  of 
tumors  produced  by  the  action  of  /Ecidium  elatinum.  He  fur- 
thermore points  out  that  such  cysts  attain  their  greatest  devel- 
opment and  largest  number  in  the  region  of  greatest  stimulation, 
i.e.  in  the  middle  of  the  tumor,*  decreasing  above  and  below 
until  they  eventually  become  pointed  and  finally  disappear  be- 
tween four  tracheids  "which,  in  their  meristematic  condition,  prob- 
ably function  as  epithelial  cells."  It  is  unfortunate  that  the 
histological  details  of  these  cysts  and  their  endings  are  not  given, 
since  such  facts  would  serve  to  throw  much  light  upon  the  rela- 
tion of  the  cysts  to  similar  structures  in  normal  tissues,  but 
there  is  no  reason  to  suppose  that  they  differ  in  their  essential 
structure  from  those  which  occur  in  the  normal  tissues  of  the 
same  or  other  species.  The  tracheids  above  referred  to  are  un- 
doubtedly parenchyma  tracheids,  and  it  is  probable  that  further 
examination  would  show  that  they  ultimately  replace  the  resin 
cells  remaining  over  after  the  disappv^.  -ce  of  the  cyst  proper. 
Tubeuf  has  also  shown  (72,  44)  that  resin  canals  are  irregu- 
larly formed  and  greatly  multiplied  through  the  action  of  para- 
sites, quoting  the  case  cited  by  Hartig  in  which  the  resin  canals 
of  the  spruce  were  found  to  be  so  numerous  in  trees  attacked 
by  Agaricus  melleus  as  to  give  rise  to  an  abnormal  production 
of  resin,  which  flows  from  the  roots  and  characterizes  the  disease 
called  resin  gland  or  resin  Jinx.  He  also  points  out  that  a 
similar  flu.x  occurs  in  the  bark  of  the  pine,  due  to  the  action  of 
Peridermium  pini.  The  action  is  therefore  developed  in  such 
a  way  as  to  induce  a  greater  activity  in  the  formation  of  wood 
parenchyma,  which,  in  Juniperus  communis,  when  attacked  by 

1  A  precisely  similar  relation  in  development  has  been  noted  by  Jeffrey  (2J) 
in  the  case  of  Sequoia  Penhallowii. 


RESIN  PASSAGES 

Gymnosporangium  clavarircforme.  often  forms  somewhat  exten 
sive  wedge-shaped  masses  projecting  between  l.^^^""^  J^^""' 
cheids  <72   jSSS     a  ^i         t'^"J«'^"ng  between  the  rows  of  tra- 
cneids  (72.  388).    A  close  comparison  of  such  a  tissue  with  that 
of  the  resm  cysts  of  Abies  shows  that  the  two  are  essentLliv 

More  recently  Jeffrey  (24)  has  contributed  an  important  mner 

may  also  be  produced  experimentally  by  iniurv  thn.V     fi      ■ 

^he.r  ongm.    The  most  significant  facts,  however,  relate  to  the 
normal  occurrence  of  such  cysts  in  Sequoia.    He  shows  in   he 
first  ms^.nce  that  they  are  absent  fr^m  the  wood  of "   V's 
year  s  growth  m  S.  sempervirens.  while  they  are  present  for  the 
same  penod  of  growth  in  S.  gigantea.  though  absen    from    he 
growth  of  later  years.    In  both  species  they  arise  in  the  ear  i^r 
spnng  wood.    In  the  case  of  S.  PenhallowH  from  th    M be  ne 
the  same  author  directs  attention  (25)  to  the  occurrence  orcl 
passages  m  both  a  radial  and  longitudinal  direction,  and  e    ab 
.shes  important  relations  between  them.    The  somewhat  "trict 
Realization  of  the  latter  and  their  obvious  connection  with  i^  ^^ 
n  well-defined  instances  leads  him  to  the  conclusion  that  theT 
re  wholly  traumatic.    This  rule  he  also  applies  to  all  cases  of 
tangentially  disposed  resin  cysts  or  resin  passages  such  as  occu 
-nSe  sempervirens.  thereby  making  it  in'clude  al,  sim 

cases  in  the  various  species  of  Abies  and  Tsuga 

that     ,esm  canals  occur  in  the  ligneous  bundles  of  the  same 

Abet  wh.ch   possess   horizontal  canals  in  the   medullary 

which  .    "  ',    "       '"^  ^'■"^^  '""^^^"^y  '"  ^"  those  cases 

cases  of  resm  cysts  as  occur  in  Abies  and  Tsuga  (59)     It  also 


«j 


1  li 
^1 


142 


ANATOMY  OF   IHE  GYMNOSFERMS 


fails  in  the  case  of  Sequoia  sempervirens  and  S.  Langsdorfii  (46), 
and  it  likewise  appears  to  fail  in  the  case  of  S.  Burgessii,  but  in 
this  latter  case  it  is  possible  that  there  is  the  same  peculiarity  of 
distribution  which  Jeffrey  has  observed  in  S.  Penhallowii,  accord- 
ing to  which  local  areas  may  oe  devoid  of  longitudinal  canals 
while  radial  ones  may  be  present. 

As  presented  by  existing  species,  Pseudotsuga,  Larix,  Picea, 
and  Pinus,  without  exception,  show  resin  passages  in  both  the 
radial  and  longitudinal  positions.  In  transverse  section  they  are 
scattered  throughout,  sometimes  appearing  chiefly  in  the  sum- 
mer wood,  sometimes  chiefly  in  the  spring  wood,  or  again  about 
equally  in  the  two  regions,  and  they  rarely  conform  to  the  pre- 
cise law  stated  by  De  Bary  (13,  495)  that  "  they  lie  scattering 
in  a  ring  in  the  external  region  of  every  annular  layer."  The 
constancy  of  their  occurrence  in  the  four  genera  mentioned  in- 
volves very  few  features  which  call  for  special  comment.  In 
Pseudotsuga  and  Larix  the  resin  passages  are  scattering.  They 
sometimes  unite  in  pairs  so  as  to  form  short  tangential  series, 
and  they  thus  approach  the  type  of  Tsuga  or  Abies,  while  yet 
again  they  may  become  definitely  isolated  and  scattering,  thereby 
approaching  the  distribution  of  Picea  and  Pinus.  In  Larix  occi- 
dentalis  the  tendency  to  a  primitive  form  of  distribution  is  ex- 
pressed in  the  formation  of  a  tangential  zone  essentially  similar 
to  that  of  Tsuga  Mertensiana.  In  both  Pseudotsuga  and  Larix 
there  is  an  obliteration  of  resin  cells  from  all  parts  of  the  struc- 
ture except  the  extreme  outer  face  of  the  su:  'ir  2r  wood.  In 
Picea,  however,  without  exception,  there  is  a  '  iplete  oblitera- 
tion of  all  resin  cells  except  such  as  enter  int^  the  structure  of 
the  resin  passages,  and  this  is  directly  correlated  with  ?  higher 
type  of  structure  in  such  passages. 

In  the  genus  Pinus,  as  already  shown,  the  resin  passage 
reaches  the  highest  degree  of  organization  in  all  respects.  It 
shows  little  if  any  tendency  to  those  primitive  associations  which 
are  expressed  in  the  formation  of  tangential  series,  while  it  lias 
entirely  placed  the  isolated  resin  cells,  which  are  never  to  be 
found  in  tnat  genus. 


RKSIN   PASSAGES 


'43 


If,  then,  we  ask  what  value  such  structures  have  for  taxo- 
nom,c  Hrposes.  wc  find  them  to  be  of  well-defined  importance 
It  has  already  appeared  that  in  Tsuga  the  cKcurrencc  of  resin 
cyst,  .8  of  well-defined  value  for  specific  differentiation,  and  the 
same  rule  is  also  applicable  to  Sequoia  sempervirens  and  to  four 
species  of  Abies.    In  the  higher  Abietinea;.  inclusive  of  Pseu 
dotsuga,  Larix,  Picca,  and  Pinus,  the  invariable  association  of 
resm  passages  in  the  wood  and  in  the  medullary  rays  not  only 
serves  to  separate  these  genera  from  all  those  in  which  resin  cysts 
only  may  occur,  but  it  also  differentiates  them  absolutely  from 
all  the  remaining  genera.   Such  association,  therefore,  constitute, 
a  feature  of  great  value.     More   particularly,  the  thin-wallcd 
epithelium  of  Pinus  at  once  separates  that  genus  from  the  other 
three,  which  are  invariably  characterized  by  thick-walled  epithe- 
hum.    Such  generic  differentiations  arc  greatly  emphasized  by 
the  occurrence  of  thyloses.    These  are  typically  developed  in 
I'inus.  where  they  are  always  thin-walled  and  almost  inNariably 
present.    They  are.  therefore,  of  definite  value  as  supplementing 
other  features  previously  described.    In  the  other  genera  how- 
ever,  their  presence  in  either  the  cyst  or  the  resin  passage 
where  they  are  generally  thick-walled,  is  of  so  sporadic  a  nature 
as  to  give  them  no  definite  value,  and  we  therefore  find  that  for 
specific  diagnoses  such  structures  may  be  neglected. 

We  are  now  in  a  position  to  present  an  answer  to  the  ques- 
tion,  How  are  the  resin  passages  related  to  the  phylogeny  of 
the  Coniferales.?  In  order  to  present  an  intelligent  answer  to 
this  question,  it  will  be  necessary  to  recall  the  facts  already 
discussed  m  connection  with  the  resin  cells,  and  bring  them 
mto  relation  with  our  discussion  of  the  resin  passages. 

In  the  genus  Sequoia  it  has  been  shown  that  the  general 
course  of  development  of  the  resin  cells  is  essentially  the  same 
as  m  Cupressus,  etc.,  while  it  has  also  been  shown  that  the  genus 
presents  in  other  respects  a  somewhat  remarkable  deviation 
Of  the  two  existing  species  both  show  the  distribution  of  the 
rcsin  cells  to  be  of  the  typically  primitive  form,  i.e.  scattering 
Nevertheless  there  are  also  in  Sequoia  sempervirens  definitely 


144 


ANAl-OMY  OF  THE  (iYMNOSPERMS 


i»rganizeil  i  tin  cysts,  but  without  exhibiting  the  transitional 
form  of  a  /.onate  disposition.  Among  fossil  representatives  Pen- 
hallow  (4.J,  i  )  has  shown  precisely  the  same  feature  to  be 
present  ii.  S.  Langsdorfii.>  This  is  the  less  remarkable,  how- 
ever, because  'It  species  is  undoubtedly  the  ancestral  form  of, 
and  practical!'  lentical  with,  S.  sempervirens.  The  fact  made 
clear  by  ',  .11.^  a4,  457)  that  resin  cysts  occur  in  the  first 
annual  ri:  _  -u  ^i,  orous  branches  of  adult  trees,  as  well  as  in 
H  ntea,  also  tends  to  make  it  apparent  that  the 
a  very  striking  advance  upon  even  the  type 
T  Tus,  since  the  aggregation  of  resin  cells  and 
•  .  ,  *"  '•  T  jm  has  arisen  abruptly,  and  with- 
...  pjcsented  by  Juniperu-.  and  Taxodium. 
.  '<>ia  IS  obviously  related  to  Thuya  and 
K  hand,  it  is,  on  the  other  hand,  related  to 
in  this  sense  it  may  be  regarded  as  the 
terminal  member  of  .1  ilovelopmental  series  embracing  the  Taxo- 
diinae,  Cupressineac,  Taxoideae,  as  follows : 


the  root- 
genus   p  i:.i;:ii     a 
exhibited  hy  '\    :y 
the  fonr  u  <.  ■  c  , 
out  the  tr.itisilionn 
While,   th.  •  .f.w 
Cupressus.  on  thi 
such  tyiK's  as  A\<1 


1.  Taxus  and  Torreya. 

2.  Thujopsi.s. 

3.  Crj'ptomeria. 

4.  Podocarpus. 

5.  Cupressus. 


6.  Thuya. 

7.  Libocedrus. 

8.  Taxodium. 

9.  Juniperus. 
10.  Sequoia. 


In  the  Abietineie  a  new  .series  is  presented.  This  is  not  in 
any  sense  strictly  conterminous  with  the  first,  but  the  two  appear 
to  make  a  fault,  as  it  were,  whereby  there  is  a  lateral  disphco- 
ment,  but  of  such  a  nature  that  Sequoia  still  serves  as  the  con- 
necting link.  Within  the  eleven  species  of  Abies  investigate 
three  important  phases  are  presented,  —  (i)  resin  cells  scattering 
on  the  outer  face  of  the  summer  wood,  (2)  resin  cells  j,Toupe(i 
and  forming  cysts,  and  (3)  resin  cells  entirely  wanting.  Viewini; 
these  phases  in  the  order  given,  it  is  to  be  observed  that  in  those 

'  While  Jeffrey  has  shown  (t»)  that  in  S.  Penhallowii  the  resin  clU  are  nor 
mally  confined  to  the  outer  face  of  the  summer  wood. 

*  This  latter  relation  has  been  recently  emphasized  by  Jeffrey  (SS)  througi. 
studies  relating  to  S  Penhallowii,  and  it  is  in  direct  confirmation  of  conclusions 
already  reached  by  Her.hallow  (44)  on  the  basis  of  other  data. 


RtSlN  PASSAGES 


M5 


four  tpeciM  which  develop  cysts  only  one  »how«  isolated  resin 
cells,  and  it  is  probably  correct  to  interpret  the  variation!  notcnl 
a»  exprestions  of  developmental  phases  in  such  a  way  that  the 
occurrence  of  cysts  represents  the  highest  position.    The  genus 
Tsuga  IS  closely  related  to  Abies  in  the  occurrence  of  isolated 
rcsm  cell!  on  the  outer  face  of  the  summer  wood,  as  also  in  the 
formation  of  resin  cysts,  but  it  obvi<,usly  occupies  an  inferior 
position  because  (i)  of  the  greater  abundance  of  resin  in  the 
individual  cells,  and  (2)  the  occurrence  of  definite  aggregates  of 
resm  cells  without  the  formation  of  cysts.    This  series  is  directly 
extended  by  those  genera  in  which  definite  resin  passages  re- 
place the  simple  cysts,  since  the  latter  are  convertible  into  the 
ormer  by  easy  and  natural  transitions.    Both  Pseudotsuga  and 
I-irix  occupy  equivalent  positions  because  they  not  only  present 
resui  passages  of  an  equal  degree  of  development,  but  t„oy  also 
show  a  survival  of  the  isolated    csin  cells  on  the  outer  *irc  of 
the  summer  wood.    Their  a«fin.t<es  are  therefore  directly  with 
Abies  and  Tsuga  un  the  lower  side,  but  oi   the  upper  side  their 
alliance  ,.  with  Picea,  which  presents  a   very  similar  though 
somewhat  higher  organization  of  the  resin  passage  and  a  com- 
plete  obliteration   of   the   isolated  resin  cell.    Yet  again    the 
structure  of  the  resin  passage  in  Picea  at  once  connects'  that 
Kcnus  with  Pinus  in  which  the  most  compler-  develo  >ment  is 
•named,  and  it  therefore  terminates  the  series  upwardl). 

Having  special  reference  to  the  particul.  forms  of  the  secre- 
tory reservoirs,  and  leaving  out  of  account  all  thcr  consi.  a- 
tions  than  their  particular  evolution,  it  is  poss  ',le  to  indi  te 
the  general  sequence  of  the  Renera,  and,  to  a  m  e  lit  ed 
extent,  of  their  specie-   as  foll-.ws  : 


I.  Tsuga  caro- 
liniana. 
TsuKa   Mer- 
tensian.i. 


2.  Abies  bracteata. 
Abies  firma. 
Abies  noi)iIi.s. 
Abies  conrnlor. 


From  this  it  is  manifest  that  Sequ- 
Abies,  but  inferior  to  Pseudotsu'ra. 


;  Sequ    a. 

4  Pseu»;ot.suga  and  Larix. 

5  !'ia 
6.  I'int  -. 

is    npcrior  to  Tsuga  and 
rix.  <.   c.    Hut  if  we  now 


— 0--         •  •">  ^    '•     "v'l  II   wc  now 
View  the  general  phylogeny  with  reference    u  ihc  entire  course 


I 


146  ANATOMY  OF  THE  GYMNOSPERMS 

of  development  of  the  resin  cells  and  the  resin  passages,  the  rela- 
tions just  explained  must  be  modified  with  reference  to  the  partic- 
ular position  of  Sequoia,  and  the  sequence  would  then  become : 

1.  Thujopsis  and  5.  Libocedrus.  10.  Abies. 

Cryptomeria.  6.  Taxodium.  1 1 .  Pseudotsuga  and 

2.  Podocarpus.  7.  Juniperus.  Larix. 

3.  Cupressus.  8.  Sequoia.  12.  Picea. 

4.  Thuya.  9.  Tsuga.  13.  Pinus. 

But  it  may  assist  in  the  general  argument  to  view  this  ques- 
tion from  another  standpoint.  Regarding  the  resin  cells  and  the 
secretory  reservoirs  as  falling  within  a  definite  series,  we  may 
apply  to  the  various  forms  of  distribution,  and  to  the  various 
grades  of  resin  reservoirs,  arbitrary  values  of  such  a  nature  as 
to  represent  our  conception  of  their  relative  positions  in  the  scale 
of  development  as  expressed  by  percentages,  thus  : 

Resin  cells  scattering 25.0% 

Resin  cells  zonate 37. j 

•Resin  cells  grouped 50.0 

Resin  cells  on  the  outer  face  of  the  summer  wood,  as  in 

Pseudotsuga  and  Larix 12.5 

Resin  cells  on  the  outer  face  of  the  summer  wood,  as  in 

Abies  (partial  only) 5.0 

Resin  cells  wholly  wanting 0.0 

t  Resin  cysts,  as  in  Tsuga,  Abies,  and  Sequoia 70.0 

Resin  passages  with  constrictions,  as  in  Pseudotsuga,  Larix, 

and  Picea 80.0 

Resin  passages  without  constrictions  and  of  the  highest  type 

of  organization,  as  in  Pinus loo.o 

We  obviously  have  two  subordinate  series  here,  which  for 
convenience  may  be  regarded  as  conterminous,  but  which,  as 
already  shown,  are  "  faulted  "  in  such  a  way  that  the  grouped 
resin  cells  (•)  and  the  resin  cysts  (f)  jointly  represent  the  point 
of  divergence  for  two  separate  courses  of  development,  the 
latter  continuing  upward,  while  the  former  descend  and  thereby 
represent  degradation.  These  features  are  best  exhibited  graph- 
ically, and  the  accompanying  curves  clearly  show  how,  on  the 
one  hand,  resin  cysts  and  resin  passages  directly  result  from 


lOOl 


ifl 


Fig.  45.   Curve  showing  the  approximate  development  of  resin  passages 
and  the  corresponding  obliteration  of  resin  cells  ^ 


M7 


148 


ANATOMY  OF  THE  GYMNOSPERMS 


Hit- 


special  modification  of  cell  aggregates,  while,  on  the  other  hand, 
from  the  same  starting  point,  there  arises  a  course  of  degrada- 
tion which  finally  results  in  the  complete  obliteration  of  the 
resin  cell  as  an  independent  structure. 

The  facts  thus  far  set  forth  have  thrown  important  light  upon 
the  general  course  of  development  of  certain  anatomical  features, 
and  they  also  show  the  general  course  of  development  for  genera 
and  species  with  reference  to  particular  structures.  They  do  not, 
however,  convey  any  information  with  respect  to  the  origin  of 
the  phylum  as  a  whole,  or  the  relations  of  the  particular  genera 
and  species  from  the  standpoint  of  collective  data,  and  such  a 
discussion  will  be  more  appropriately  reserved  for  the  general 
summary.  1  ..ere  is,  however,  one  feature  arising  out  of  recent 
investigations  which  calls  for  consideration  at  this  point,  since 
certain  of  the  conclusions  reached  are  not  in  harmony  with 
our  own,  the  divergence  of  opinion  indicated  being  the  result 
of  different  methods  of  interpretation. 

Jeffrey  states  (24,  447,  457)  that  all  such  resin  cysts  as 
occur  in  Sequoia  sempervirens  and  Abies  are  of  a  traumatic 
nature,  and  therefore  pathological.  To  this  categc/y  he  would 
also  doubtless  assign  the  corresponding  structures  of  Tsuga. 
This  opinion  appears  to  be  shared  by  Anderson  (1,  2),  and  it 
is  also  ipparently  supported  by  Pierce  (60).  Both  Jeffrey  and 
Anderson  show  that  the  development  of  such  cysts  is  sometimes 
definitely  associated  with  the  production  of  tumors  through  the 
operation  of  parasites,  and  that  they  may  also  be  induced  by 
wounds  experimentally  produced.  The  facts  they  cite  show  con- 
clusively that  resin  cysts  may  and  often  do  arise  traumatically, 
and  such  is  unquestionably  true  of  Sequoia  Penhallowii,  as  shown 
by  Jeffrey  (25)  within  the  Units  of  our  present  knowledge  of 
that  species,  but  in  such  cases  they  lie  outside  the  usual  course 
of  development. 

The  occurrence  of  resin  passages  in  the  fundamental  tissue 
of  the  Coniferales  is  a  well-known  fact,  as  pointed  out  by  De  Bary 
(13,  44')  many  years  since,  when  he  summarized  the  general 
facts  in  the  statement  that  "all  investigated  species  of  Conifeia , 


RESIN  PASSAGES 


149 


n 


reservoirs,  wh.ch  ^^ry  m  distribution  and   number  according 
to  the  spec.es.      This  statement  would  include  the  leaves  and 
bark    and  sometimes  even  the  pith  of  species  which  produce 
nather  isolated  resin  cells  nor  resin  reservoirs  of  any  kind  m 
he  xylem  tissue  of  the  stem.    It  directs  attention  somewha" 
orciWy  to  the  fact  that  while  the  occurrence  of  resin  reservoir 
m  the  fundamental  tissue  is  a  legitimate   inheritance  of  the 
mucilage  canals  of  the  Eusporangiate  ferns  and  the  Cycado- 
fihces.  as  also  later  of  the  resin  cells  of  Cordaitales.  the  xylem 
structure  is  the  very  last  to  receive  the  impress  of  such  a  cours" 
of  development;  and  it  is  therefore  in  nowise  surprising  that 
the  resin  passages  do  not  appear  there  until  a  very  late  period 
of  development,  and  that  their  organization  can  even  then  be 
brought  about  only  through  a  somewhat  prolonged  series  of 
changes  which  are  initiated  by  the  occurrence  of  isolated  resin 
cells,  much  as  the  formation  of  mucilage  canals  may  be  traced 
back  to  specialized  cells  which  separately  have  the  same  func- 
tion  in  the  Eusporangiate  ferns. 

The  local  occurrence  of  resin  passages  in  the  xylem  of  the 
Horal  axis  m  no  way  invalidates  the  obvious  conclusions  to  be 
drawn  from  these  statements,  since  it  may  be  readily  accounted 
for  in  other  ways.    In  a  structure  so  unresponsive  to  influences 
which  would  induce  profound  alterations  as  the  xylem.  it  is  to 
be  expected  that  important  structural  changes  could  be  effected 
only  after  a  prolonged  interval  during  which  the  fixation  of  any 
particular  character  would  be  preceded  by  a  period  of  sporadic 
development,  within  which  such  character  would  be  liable  to 
recur  under  special  conditions;  and  as  such  conditions  are  obvi- 
ously of  fundamental  importance,  we  may  inquire   somewhat 
more  fully  into  their  nature  and  results 

The  statement  of  Prantl  (62.  35).  that  "Those  genera  which 
are  devoid  of  resin  passages  in  the  wood  of  young  and  vigorous 
groNvth  later  produce  single  parenchyma  elements  in  the  wood 
which  contain  resin."  requires  some  modification  in  view  of  what 
Jeffrey  has  shown  in  the  case  of  Sequoia  and  Abies,  as  well  as 


ifei 


>50 


ANATOMY  OF  THE  GYMNOSPKRMS 


what  has  been  shown  in  the  course  of  the  present  studies,  and 
in  its  more  comprehensive  and  exact  form  it  should  read,  "  Those 
genera  which  are  usually  devoid  of  resin  passages  in  the  wood, 
but  some  species  of  which  may  nevertheless  contain  resin  cysts 
in  the  young  and  vigorous  growth,  later  produce  single  paren- 
chyma elements  in  the  wood  which  contain  resin." 

Taken  by  itself,  this  statement  as  applied  to  Sequoia  and 
Abies  might  be  held  to  indicate  that  the  growth  of  the  first  year 
represents  the  most  stable  structural  region  of  the  entire  stem, 
in  the  sense  that  it  embodies  characters  which  are  most  fully 
established,  and  that  it  will  therefore  embrace  elements  which 
may  be  eliminated   from   the  older  parts,  or  which  may  be 
replaced  there  by  degenerate  forms  only.    From  this  point  of 
view  it  would  be  necessary  to  regard  the  complex  resin  passage 
as  the  primitive  form  of  structure  from  which  the  cysts,  groups 
of  cells,  and  isolated  lesin  cells  have  been  derived  by  a  process 
of  progressive  degradation.    This  view  appears  to  have  been 
adopted  by  Jeffrey  (24,  454),  who  supports  his  position  by  citing 
the  occurrence  of  resin  passages  in  the  va  cular  structure  of 
the  peduncle  of  certain  fossil  Cycads,  interpreting  this  to  mean 
that  such  structures  represent  a  survival  of  features  which  have 
been  obliterated  from  the  structure  of  the  stem.    Such  a  view 
does  not  seem  to  be  in  harmony  with  the  facts  which  our  own 
studies  have  brought  out,  to  the  effect  that  resin  passages  of 
the  type  found  in  the  xylem  structure  are  in  no  sense  primitive 
or  vestigial,  since  they  are  wholly  wanting  in  the  primitive  gyni- 
nosperms,  and  their  organization  does  not  arise  until  a  very  late 
period  in  the  evolution  of  the  higher  forms.    If  our  interpretation 
of  observed  facts  is  correct,  as  applied  to  the  origin  of  the  resin 
passages,  it  shows  as  clearly  as  one  could  well  expect  a  pro- 
gressive development  from  the  isolated  resin  cell  through  vaiious 
phases  of  aggregation  to  the  highest  form  of  structure  as  found 
in  Pinus.    That  there  is  such  a  series  cannot  be  doubted,  and 
we  must  interpret  it  in  one  of  two  ways,  — either  as  progressive 
evolution  or  as  progressive  degeneration.    To  us  the  arguments 
all  seem  to  be  very  emphatic  with  respect  to  lending  support  to 


RESIN  PASSAGES 

.'he  re,::::  zizTorr"'"  ^  -"  """""■"'  •^•^  ™«™ 

.ta  .he  ,a„er  vj?,  ^Z.Z:Z::V"' ^'^  "°"''"' 

>-•  u.  u  „„„,4  fi„.  „t  „,,  „,c'e™:;,"a  *«  ;t'L;;  re 

.hat  such  a  prop„si;io„  w„„U  ml.  ^rmlr'""  '°  "«^"' 
tutes  the  most  impressionable  portions  of  the  «;f^m  J     7 

higher  pu„.s,  bu.  .hey  are  Zo  1  y  ,  rTrsT;  0?°"*,."° 
2.  Resin  passages  are  wholly  unknown  in  the  wood  of  fh. 

a^if  ihe  'l:^r":V",  °  ""-^  ■"  "^  '^'■"*»  °'  Se<,„„ia 

se,.«aptr!?:rs:-:n:;t^^^^^^^ 

5.  In  Sequoia  Burgessii,  from  the  E,-ccne    resin   n.T^' 


ill 


152 


ANATOMY  OF  THE  GYMNOSPERMS 


From  this  it  would  seem  that  the  fundamental  tissue  is  the 
most  impressionable  with  respect  to  the  development  of  these 
structures,  and  that  after  it  we  have  in  the  same  order  the 
peduncle  of  the  inflorescences  and  the  wood  of  the  young  shoots, 
to  which  latter  category  would  also  belong  the  development  of 
resin  passages  in  fasciated  stems,  and  such  a  sequence  is  pre- 
cisely what  we  should  expect  from  our  knowledge  of  the  relation 
which  the  fundamental  tissue  bears  to  other  structures.    Accord- 
ing to  this  conception  the  resin  passages  may  appear  in  any  part 
of  the  woody  structure  where  growth  is  sufficiently  vigorous, 
but  such  appearance  would  be  temporary  and  indicative  only 
of  a  future  course  of  development  which  has  not  as  yet  become 
sufficiently  well  impressed  upon  the  organism  to  form  a  perma- 
nent feature  of  it.    In  other  words,  the  tissue  exhibits  what  in 
other  cases  would  be  termed  "sports."    Such  structural  fore- 
casts are  well  known  and  of  frequent  occurrence.    As  applied 
to  the  development  of  tissues,  no  better  example  is  afforded  than 
that  shown  by  the  central  strand  of  mosses,  which  is  generally 
accepted  as  prophetic  of  the  future  vascular  system  in  the  spo- 
rophyte,  and  they  serve  to  suggest  that  the  law  of  mutation  as 
proposed  by  De  Vries  finds  expression  in  the  evolution  of  internal 
structures  as  well  as  in  the  development  of  external  forms.   Such 
cases  as  Sequoia  gigantea,  which  shows  resin  cysts  in  the  wood 
of  the  first  year  and  nowhere  else,  being  replaced  later  by  resin 
cells,  appear  to  us  to  show  that  young  and  vigorous  growth  in 
general,  and  therefore  the  growth  ring  of  the  first  year,  consti- 
tutes a  transitional  zone  within  which  many  changes  of  structure 
wholly  apart  from  the  strictly  normal  may  arise;  and  such  a 
law  would  similarly  be  applicable  to  the  wood  of  peduncles. 
This  feature  is  manifested  in  the  structure  of  the  medullary  ray, 
the  character  of  the  tracheids  as  exhibited  in  transverse  section, 
the  genesis  of  the  bordered  pits  from  spiral  tracheids,  and,  in  all 
probability,  also  in  the  formation  of  resin  passages  in  Sequoia 
and  Abies,  as  noted  by  Jeffrey. 

Changes  of  this  nature  are  to  be  regarded  as  tendencies  in 
development  in  the  direction  of  higher  types  of  structure,  whereby 


RESIN  PASSAGES 

potentialities  assume  a  more  or  less  definite  for™     p 

may  be  assumed  that  the  primarrRrowth  rinJT"  '*"'  '' 

The  considerations  dealt  with  here    as  wpH  oc  • 
Chapters,  lead  us  to  give  renewed  TrnpLr  /    :L^^r: 
has  been  expressed  elsewhere,  and  which  finds  justiic^tiL  t 
many  v^ys  no,  ,„,y  j„  ^,^  gymnosperms  but  in  the  sTl  "^ 
and  m  Catalpa  among  the  angiospems.  to  the  effe.!  fh 

primary  .mportance.  and  such  changes  are  no  dou^etbl^h^ 
external  morphology  in  questions  of  classificatioa 


CHAPTER  XI 

GENERAL  PHYLOGENY 

The  results  to  which  we  are  now  brought  are  based  entirely 
upon  developmental  phases  in  anatomical  elements  of  the  vas- 
cular cylinder.    While  our  studies  lead  to  certain  definite  con- 
clusions, we  do  not  in  any  sense  regard  these  as  final,  but  only 
as  affording  one  step  in  the  solution  of  a  question  which  must 
be  viewed  not  only  from  the  broader  standpoint  of  more  extended 
anatomical  data  but  also  from  that  of  physiology  as  well,  although 
we  feel  disposed  to  insist  that  the  final  answer  will  be  found  to 
rest  chiefly  upon  an  anatomical  basis.    That  there  may  be  room 
for  a  different  interpretation  of  the  facts  here  recorded  is  quite 
possible,  since  Dr.  Jeffrey  has  recently  permitted  me  to  exam- 
ine the  manuscript  of  an  important  contribution  to  our  knowl- 
edge of  the  Abiecineae,  in  which  he  brings  out  very  significant 
facts,  which  suggest  that  the  group  is  of  a  much  more  primitive 
character  than  has  hitherto  been  supposed  or  than  is  indicated 
by  our  own  studies.    It  is  therefore  of  importance  that  final 
judgment  should  be  suspended  until  the  results  of  these  various 
studies,  as  well  as  those  of  Coulter,  Chamberlain,  and  Ferguson, 
all  directed  to  the  same  end  but  prosecuted  along  somewhat 
different  lines,  can  be  brought  together  and  coordinated.    It  is 
in  this  sense  that  the  following  conclusions  are  offered. 

In  discussing  the  phylogeny  of  the  higher  gymnosperms 
three  subordinate  phyla  must  be  taken  into  consideration  in  the 
following  order:  (i)  Cordaitales,  (2)  Gingkoales,  (3)  Coniferales. 

Regarding  the  Cordaitales  a"  the  most  primitive  gymnosper- 
mous  stock  of  which  we  have  present  knowledge,  it  is  possible  to 
trace  its  origin  to  the  Cycadofilices.  The  genera  Lyginodendron, 
Heterangium,  and  Calamopitys  present  many  structu;  .  'eatures 
which  are  common  to  all,  and  which  not  only  cstabl^^h  their 

'54 


i  "1 


GENERAL  PHYLOGENY  ,-- 

relation  to  the  Cycadean  line  of  descent  but  also  offer  many 
suggestions  of  that  course  of  development  which  is  realized  in 
the  higher  Conifen^les.   They  therefore  constitute  the  re     ^art" 

he  Cycadales     At  the  present  moment  we  have  little  or  nothin. 
to  do  with  th,s  beyond  establishing  its  probable  relation  to    hf 
other  gymnosperms.    The  second  line  emerges  in  a  type  of  plant^ 
having  charactensfcs  distinctly  allied  to  those  of  the  Coil 
and  U  IS  this  line  of  descent  with  which  we  are  now  chiefly  coni 
cerned^    t  ,s  now  possible  to  define  the  origin  of  this  phylum 
somewhat  more  exactly  than  Coulter  has  done  (11.  W)    ^nc^ 
there  •«  good  reason  to  believe  that  it  emerges  from  the  Cycad<! 
fihces  through  Poroxylon.    Scott  (81.  398)  has  already  pobt^ 
out  the  relations  of  this  genus  to  the  Cycadofilices  and  Z 
Cycadaceae  on  the  one  hand,  and  to  Cordaites  on  the  other  so 
clearly  as  to  remove  the  necessity  for  detailed  discussion  at  t'his 

eTat'ion?"";    cT'  ""^''''''  '°  °"'  ""'  '*°  ''"P°'^^"^  «*r"<^tural 
relations.    In  Calamopitys  saturni  it  has  been  noted  that  the  most 

primitive  distribution  of  the  bordered  pits  upon  both  the  ndil 

Such  hTk      """u  "  '"P"""**^'  •"  '""^  P-^-y'--"  structure 
Such  distribution,  however,  undergoes  rapid  modification  where- 
by  It  IS  wholly  limited  to  the  radial  walls  in  the  secondary  wood 
A  ..milar  limitation  appears  in  other  somewhat  closely  related 
genera,  and  it  is  fully  expressed  in  Poroxylon.  where  the  muhl- 
senate  disposition  and  hexagonal  form  are  typically  preserved 
though  there  is  at  the  same  time  a  tendency  to  se^^gation  to 
such  an  extent  that  the  pits  sometimes  become  round     In  this 
1^  .s  possible  to  notice  the  first  indication  of  a  character  which, 
the  r  '"!7r '' '^  nevertheless  occasionally  expressed  among 
the  Cordaitales  though  it  is  generally  characteristic  of  the  related 
pnyla,  Gmgkoales  and  Coniferales. 

Among  the  Cordaitales  there  is  but  one  genus  (Cordaites)  which 
^^  eaave  heretofore  been  accustomed  to  associate  with  that  phylum 

nd  so  far  as  our  present  knowledge  goes,  it  undoubtedly  stands 
^    the  d       t  ,,,,,i^„^  ^^  p^^^^yj^^     j^  .^^  ^^^^^^^^       >^^^^^^ 

that  the  two  were  m  any  sense  conterminous,  and  it  is  altogether 


156 


ANATOMV  OF  THE  GYMNOSPERMS 


probable  that  there  may  have  been  some  one  or  more  intermediate 
forms  of  which  we  have  no  present  knowledge.  Our  present 
studies,  on  the  other  hand,  show  clearly  that  we  must  bring  into 
this  phylum  two  other  genera  of  an  obviously  higher  degree 
of  development,  but  which  have  commonly  been  ranked  with 
the  Abietinex  and  which,  according  to  Eichler  (15),  occupy  the 
highest  position  in  the  scale.  This  position  is  untenable  upon 
anatomical  grounds  which  give  us  reason  to  believe  that  Dam- 
mara  and  Araucaria  (including,  of  course,  Araucarioxylon)  are 
not  only  inferior  to  the  Coniferales  as  a  whole  but  that  they  are 
also  distinctly  Cordaitean.  Accepting  this  view  and  the  fact 
that  Dammara  is  the  inferior  genus,  the  sequence  would  place 
Cordaites  at  the  base  and  Araucaria  at  the  top,  with  Walchia  as 
the  immediately  ancestral  form  of  the  latter.  This  relation  is  not 
only  natural  but  it  is  justified  on  anatomical  grounds. 

The  tendency  to  segregation  of  the  bordered  pits,  as  exhibited 
by  Poroxylon,  suggests  the  relation  of  this  genus  to  others  in 
which  such  a  feature  is  fully  expressed,  and  it  thereby  forms  the 
basal  member  of  another  series.  From  the  opposite  point  of  \iew 
it  has  been  shown  that  the  occurrence  of  two-seriate  pits  in  Pinus 
and  others  of  the  Coniferales,  as  well  as  in  Gingko,  points  to  a  com- 
mon origin  for  such  genera  in  a  type  with  multiseriate  hexagonal 
pits,  and  that  both  Dammara  and  Araucaria  must  likewise  center 
in  the  same  generalized  form.  This  gradual  convergence  is  justi- 
fied on  other  grounds,  and  the  genus  Poroxylon  among  known 
forms  most  nearly  fulfils  the  requirement*  of  the  case.  We  may 
therefore  look  upon  it  as  lying  between  the  Cycadofilices  and  all 
the  higher  gymnosperms,  giving  rise  to  two  lines  of  descent,  the 
first  of  which  embraces  the  Cordaitales,  as  already  described,  while 
the  second  shortly  divides  once  more.  This  secondary  division 
gives  rise  on  the  one  side  to  the  Gingkoales,  and  on  the  other  to 
the  Coniferales.  The  anatomical  data  already  discussed,  when 
viewed  collectively,  show  that  the  general  sequence  within  the  lat- 
ter would  be  (I)  theTaxoideae,  (2)  the  Taxodiinx,  (3)  the  Cupres- 
sineae,  (4)  Abies,  (5)  Tsuga,  (6)  Pseudotsuga,  (7)  Larix,  (8)  Picea, 
and  (9)  Pinus,  of  which  one  division,  (II),  represents  the  highest 


GENERAL  PHYLOGENV  ,-- 

type  of  development     With  respect  to  the  precise  position  of 
Seqaou  .„  particular,  us  relation  to  Abies  on  the  one^aTand 

ntor  t  ''  ' ''"'"  °'  our  knowledge,  to  indicate  it,  origin 
from  or  .ts  ancestry  to  either  of  them.  The  facts  derived  frfm 
anatomy,  however,  do  indicate  a  more  or  less  common  ori^n  fo  aH 
^ur  genera,  and  from  this  point  of  view,  taking  into  account  th" 
pecuhar  futures  exhibited  by  Sequoia,  they  would  seem  to  justify 
the  .dea  that  that  genus  represents  a  short  side  line  of  deveW 
ment  ^vh.ch  does  not  lead  to  the  evolution  of  other  typeTbu^ 
tcrmmatesm  S.  gigantea  after  a  comparatively  brief  per^Thl 
sequence  of  species  for  each  genus  cannot  al^ys  beTe^rmilL 

2t  yi  TT  '^  ^^"f^«'°".  ^d  these  difficulties  may  Z 
•bly  be  nude  clear  by  reference  to  the  succession  of  the  Z. 
pec.es  of  Sequoia,  which  is  difficult  to  determine  on  purely  ana 
om.cal  grounds,  but  the  general  tendency  of  the  facts  a^ 
ected  «  o  give  to  S.  sempervirens  the  more  primitiveTosf 
"'h7reir  t^'  'r"^'^'""'  'y  '^^  Paleontol^gi™!  ;  St'; 

reaLns  orT  CO  T  '  "'  "  ^'^  '°"^°'"^  ''-^'^'  -^  t7e 
w'thou  ^°V^;;°-^^'"^'«"«  >-^-hed.  may  be  made  more  obvious, 
without  the  tedious  method  of  a  detailed  discussion,  by  refer 
ence  to  the  accompanying  table  of  anatomical  data  (AppZ^Z 
wh.ch  substantially  summarizes  all  the  results  deriveTf rom  fht 
study  of  particular  structures.  In  preparing  this  table  the  vTriouI 
anaom.cal  features  have  been  chosen  with  reference  to  "h 

and  (3)  their  obvious  relation  to  diagnostic  purposes.  In  thei^ 
horizontal  extension  an  attempt  has  been  maLrarrange  4em 
n  accordance  with  the  law  of  frequency,  as  well  as  with  ^fferen" 
o   he    re,^,,^„  to  development,  in  such  wise  that  while  the  s^! 

mlvK    K  u    ^'"'""  °^  '*°  ^•"''^  °^  «"»  '"  the  medullary  ray 
may  be  held  to  express  the  highest  form  of  development    To 

while  those  subordinate  characters  which   are  represented  by 


I 


■58 


ANVTOMY  OF  THE  GYMNOSPERMS 


different  forms  of  di»tributbn  may  be  regarded  as  forming  a 
second  series  similarly  valued.    Any  primitive  or  other  character 
which  has  become  obliterated  through  development  may  be  held 
to  retain  its  original  value  with  respect  to  the  general  course  of 
such  development,  and  it  it  always  indicated  by  -.    Vestigial 
structures  occurring  sporadically  ane  designated  by  i,  and  to 
them  one  half  the  value  of  the  fully  devel«»ped  character  is 
assigned.     All   normal   features  are   designated   by  x,    which 
becomes  x  +  when  they  show  deveJopment  toward  the  next 
higher  form,  or  x  -  when  they  show  a  definite  tendency  to  degen- 
eration.   Sporadic  characters  which  are  obviously  in  the  line  of 
development  are  indicated  by  o,  but  they  are  assigned  only 
half  values.    On  this  basis  it  is  possible  to  arrange  a  sequence  of 
genera  and  species  in  such  a  manner  as  to  exhibit  a  progressive 
development  from  the  simple  Dammara,  with  a  minimum  of  char- 
acteristics, to  the  complex  Pinus,  in  which  the  greatest  number 
of  anatomical  features  is  involved.    Furthermore  through  such  a 
series  it  is  possible  to  determine  the  relative  position  of  the  vari- 
ous genera  by  percentage  values,  and  it  gives  the  most  valuable 
insight  into  the  approximate  relations  of  the  various  members 
within  the  general  line  of  descent.    Such  relations  are  determined 
not  only  for  each  anatomical  character  but  also  for  the  collective 
characters.    Reducing  these  facts  to  a  graphic  form,  the  accom- 
panying curves  wUl  assist  in  making  the  relations  more  clear, 
especially  in  emphasizing  the  general  course  of  development,  and, 
in  their  final  form,  they  are  best  expressed  by  a  biological  tree.    A 
figure  of  this  sort  is  diflScult  to  construct,  and  there  is  no  agree- 
ment among  investigators  as  to  the  p;   ticular  form  it  should  take. 
While  the  figures  in  common  use  indicate  a  certain  relationship 
in  descent,  th  ey  completely  fail  to  convey  any  impression  of  the 
way  in  which  the  succession  arises,  and  they  furnish  no  indica- 
tion of  possible  gaps.    They  therefore  constitute  a  very  poor 
working  basis. 

In  teaching  I  have  long  been  accustomed  to  compare  the 
various  lines  of  descent  among  plants  with  the  branchings  of 
a  deliquescent  tree,  since  it  has  always  seemed  reasonable  to 


GENERAL  PH    LOCJENV 


>59 


suppoM  that  the  laws  which  «•'"  n  the-  I.  mching  of  a  hmb 
which  give  rise  to  a!I  the  varying  i.,rms  of  a.  .ted  tlevelopmcnti 
and  which  thereby  determine  a  p^ulicular  modification  of  the 
hgure  which  would  otherwise  result  from  unmodifieri  g,.wlh. 
must  be  equally  applicable  to  the  general  evolution  of  the  hi^'her 
forms  of  plants  from  a  common  juicestral  type.  In  endeavor- 
ing to  secure  a  nai  jral  growth  which  would  best  exprcs*  all  the 


lOO' 


'    ■!    3    4    S    6    7    8    9   lo  II  12  1  5  I  t  l.S  l6  17  l8  19  ;o  Ji  22  23  J4  25  211 
Fu.  46    Carves  for  sequence  of  genera  and  frwjuency  of  anatomical  characters 
of  the  Cordaitales.  Gingkoules.  a..d  Coniferales :    ./.  sequence  of  genera- 
ff,  specific  characters;  C,  generic  character-^ 

conditions  in\  olved,  the  branching  system  of  the  Norway  maple 
(Acer  platanoides)  seems  best  suited  to  an  illustration  of  all  these 
Iihasesof  terminal  growth,  suppression,  and  relations  of  successive 
members  which  we  conceive  to  be  re[)rescnted  in  the  development 
of  plant  phyla,  inasmuch  as  it  conveys  the  idea  of  succession 
through  lateral  members  in  such  a  way  as  to  indicate  the  chief 
hne  f  de  .ent.  The  branch  of  the  Norwav  maple,  when  of  vigor- 
ous fero*th,  is  a  monopodium,  and  tt  is  oh\)ous  that  such  would 


i6o 


ANATOMY  OF  THE  GYMNOSPERMS 


not  answer  the  object  in  view,  since  its  most  prominent  feature 
would  suggest  the  idea  of  a  continuous  series  of  conterminous 
members,  from  which  lateral  members  would  arise  at  intervals. 
There  is  no  evidence  that  any  phylum  represents  such  a  series ; 
on  the  contrary,  there  is  every  reason  to  believe  that  such 
relations  do  not  exist  among  the  various  groups  of  plants. 

In  those  branches  of  the  Norway  maple  which  exhibit  slow 
growth  various  forms  of  arrested  development  are  manifested. 
These  take  the  form  of  atrophied  buds,  or  of  branches  in  all 
stages  of  development,  and  there  thus  arises  a  modified  monopo- 
dium  which  eventually  becomes,  in  many  cases  at  lerst,  a  true 
sympodium.    In  comparing  this  with  the  monopodial  branch  of 
vigorous  growth,  it  appears  that  the  alterations  involve  more 
than  mere  suppression.    In  the  monopodium  the  average  angle 
of  divergence  for  the  lateral  members  is  45 .3  degrees,  while  for  the 
derived  form  it  is  34.1  degrees.    The  latter  will  be  seen  to  com- 
pletely fulfil  all  conditions  with  respect  to  the  development  of 
a  phylum,  even  to  indicating  the  position  of  missing  members. 
In  the  construction  of  this  figure  an  attempt  has  been  made  to 
show  all  normally  developed  buds  (O)  and  their  relative  dimen- 
sions ;  atrophied  buds  (o),  the  position  of  which  is  recognizable ;  and 
atrophied  branches  (Y)  which  are  still  visible,  but  it  is  obvious 
that  the  figure  does  not  show  many  members  all  evidence  of  the 
former  existence  of  which  has  completely  disappeared.    Selecting 
from  this  we  obtain  the  accompanying  figure,  which  embodies 
our  final  conclusions  as  to  the  general  succession  of  the  different 
gyronosperms,  and  from  it  we  may  gather  that  the  highest  repre- 
sentative, Pinus,  is  the  terminal  member  in  the  main  line  of 
descent  from  the  Cycadofilices  through  Poroxylon,  while  from 
s'-h  a  central  line  both  the  Cordaitales  and  Gingkoales  have 
been  given  off  as  side  lines. 

The  general  results  of  these  investigations  serve  to  confirm  in 
a  very  striking  manner  the  probable  monophyletic  origin  of  the 
gymnosperms,  as  already  expressed  by  Coulter  (11),  while  they 
also  show  that  the  real  transition  ground,  at  least  for  all  but  the 
Cycadaceae,  was  probably  represented  by  Poroxylon,  as  indicated 
by  Scott  (81). 


<*f       \ 


I 

g 


I 


11^ 


it 


t      9 


t6i 


F  '^''^  ' 


CHAPTER  XII 

DURABILITY  OF  WOODS  AND  THEIR  PRESERVATION 
AS  FOSSILS 

One  of  the  most  important  questions  which  enters  into  the 
consideration  of  those  who  are  called  upon  to  employ  timbers  for 
the  various  constructive  purpooco  to  which  t^ey  are  adapted,  is 
their  ability  to  resist  decay  in  its  various  forms,  or  their  dura- 
bility.   Different  species  of  woods  vary  widely  in  this  respect,  as 
may  be  readily  ascertained  by  consulting  the  data  collected  by 
Professor  C.  S.  Sargent  in  his  Tenth  Census  Report  upon  the 
Forest  Resources  of  the  United  States,  and  as  appears  in  the  sec- 
ond part  of  the  present  work.    In  general  terms  it  is  probably  true 
that  the  more  resinous  woods  are  more  durable  than  those  which 
are  less  resinous,  this  being  the  direct  result  of  the  preservative 
action  of  the  resinous  material,  which  is  in  itself  highly  resistant 
to  decay,  and  which  further  acts  through  its  somewhat  well- 
defined  antiseptic  properties  and  therefore  behaves  toward  the 
general  structure  as  a  natural  preservative,  while  it  also  excludes 
water  from  the  interior  parts  and  thus  tends  to  limit  the  opera- 
tions of  fungi.    Thus  it  may  be  stated  broadly  that  the  resinous 
conifers  as  a  whole  are  more  durable   than   the  nonresinous 
woods  of  the  higher  angiosperms.    Or  among  the  conifers  them- 
selves the  hard  pines  are  more  durable  than  the  soft  pines,  as 
may  be  seen  by  a  comparison  of  the  southern  pine  (Pinus  palus- 
tris)  with  the  white  pine  (Pinus  strobus).    But  apart  from  the 
presence  of  resin,  which  may  be  localized  or  disfibuted  through 
out  the  entire  cellulose  skeleton,  it  is  altogether  probable  that  the 
durability  depends  to  a  very  large  extent  upon  inherent  projier- 
ties  of  the  cell  membranes  which  have  become  variously  modifiod 
in  the  course  of  growth  and  thus  adapted  to  this  end.   Thus  it  has 
already  appeared  (Chapter  III,  p.  48)  that  while  the  unmodified 

162 


DURABILITY  OF  WOODS 


163 


cellulose  contains  approximately  44  per  cent  of  carbon,  the  lig- 
nified  tissues  contain  upwards  of  68  per  cent  of  this  element 
From  this  we  are  led  to  conclude  that  tissues  yield  to  or  resist 
decay  just  in  proportion  to  the  extent  of  such  modifications, 
which  are  to  be  regarded  as  of  a  protective  character.    If  this 
principle  be  extended  to  lignified  tissues  in  general,  we  must  then 
admit  that  smce  the  extent  and  quality  of  the  lignification  do 
not  develop  equally  in  all  species,  these  latter  must  exhibit  corre- 
sponding differences  with  respect  to  their  ability  to  resist  the 
dismtegration  attending  what  is  commonly  called  decay,  whether 
such  decay  arises  primarily  as  a  process  of  slow  oxidation  or 
whether  it  is  initiated  through  the  operation  of  active  enzymes 
The  general  law  thus  stated  has  an  illustration  in  a  very  striking 
instance  of  the  relation  which  the  special  character  of  the  cell 
wall  bears  to  agents  promotive  of  decay,  as  recorded  by  von 
Schrenk  (68,  49),  who  shows  that  while  Polyporus  versicolor 
readily  attacks  the  living  catalpa  tree  and  produces  widespread 
decay,  there  is  no  fungus  which  will  attack  the  timber  when  once 
It  has  been  cut  and  seasoned.  —  a  fact  which  serves  to  explain  the 
astonishing  durability  of  this  wood  in  spite  of  its  great  porosity. 
Another  factor  of  great  importance  is  to  be  found  in  the  con- 
ditions which  immediately  surround  a  given  timber,  since  it  is  a 
well-known  fact  that  the  same  species  of  wood  does  not  exhibit 
the  same  degree  of  durability  under  all  conditions.    Thus  wood 
in  a  well-drained  and  well-aerated  soil  will  have  a  much  longer 
term  of  life  than  it  would  in  a  wet  and  badly  aerated  soil     Or 
again,  the  same  difference  would  hold  true  as  between  a  com- 
paratively sterile  soil  and  one  which  is  rich  in  organic  compounds. 
The  life  of  a  timber  in  salt  water  is  far  greater  than  in  fresh 
water,  or  even  than  in  well-drained  soil,  owing  to  the  specially 
preservative  action  of  the  salt ;  while  the  durability  may  be 
mdefimtely  prolonged  if  the  wood  be  hermetically  sealed  in  an 
impervious  matrix  such  as  clay.    These  differences  are  readily 
susceptible  of  an  explanation  by  reference  to  the  relation  which 
the  various  media  bear  to  the  growth  of  fungi  and  bacteria,  since 
wc  recognize  in  these  two  groups  of  plants  the  active  agents 


1 64 


ANATOMY  OF  THE  GYMNOSPERMS 


which  constitute  the  source  of  decay.  It  is  not  our  purpose  to 
discuss  the  particular  mode  of  action  of  these  organisms  at  the 
present  moment,  since  that  is  more  appropriately  reserved  for 
a  subsequent  chapter,  but  a  few  concrete  examples  will  serve  to 
indicate  somewhat  more  exactly  the  relative  durability  of  certain 
species  under  widely  different  conditions. 

One  of  the  most  instructive  examples  to  which  our  attention 
has  been  drawn,  not  only  because  of  the  very  perfect  state  of 
preservation  but  also  because  of  the  great  length  of  time  the 
wood  has  resisted  the  action  of  decay,  is  to  be  found  in  Sequoia 
Penhallowii,  as  recorded  by  Jeffrey  (25).    The  wood  in  question, 
representing  a  large  fragment  of  a  tree  at  least  six  feet  in 
diameter,  presents  the  external  aspects  of  a  recently  cut  piece 
taken   from  an  existing  tree.    It  is  of  Miocene  age,  and  was 
obtained  from  the  Sierra  Nevada  Mountains  on  the  line  of  the 
Central  Pacific  Railway,  under  sixty  feet  of  conglomerate,  where 
it  was  located  in  the  auriferous  gravels.    No  difficulty  was  ex- 
perienced in  making  sections  of  this  wood  for  the  microscope,  no 
more  than  would  be  encountered  in  wood  taken  from  an  exist- 
ing tree,  since  it  was  very  slightly  silicified.    A  microscopic 
examination  shows  the  structure  to  be  most  beautifully  and  per- 
fectly preserved  in  all  its  details ;  while  several  beautifully  pre- 
pared sections,  for  which  I  am  indebted  to  the  courtesy  of 
Dr.  Jeffrey,  also  make  it  evident,  from  the  complete  absence  of 
fungus  mycelia,  that  these  latter  had  not  found  their  way  into 
the  tissues  at  any  time  during  the  long  burial  of  the  tree.    The 
special  interest  of  this  wood  centers  in  the  fact  that,  so  far  as  I 
am  aware,  there  is  no  other  example  of  an  uninfiltrated  and 
unaltered  wood  from  so  ancient  a  formation. 

More  recent  Tertiary  strata  afford  numerous  examples  of  a 
similar  character.  The  Pleistocene  in  particular  has  furnished 
many  instances  of  the  most  perfect  conditions  of  preservation, 
chiefly  of  woods  which,  under  ordinary  circumstances,  would  be 
regarded  as  "  durable."  In  1898  Professor  A.  P.  Coleman  of  To- 
ronto obtained  from  the  Pleistocene  chys  of  the  Don  valley,  at  that 
place,  a  specimen  of  the  common  red  cedar  (Juniperus  virginiana) 


UURABIMIY  OF  WOODS 


»65 


which  exhibited  all  the  external  features  of  that  species,  includ- 
ing the  char?cteristic  color  and  fibrous  bark  (48,  562).    When 
cut  with  a  saw  the  well-known  odor  was  given  off  somewhat 
freely.    Under  the  microscope  the  structure  was  found  to  exhibit 
no  evidence  of  alteration,  while  there  was  seen  to  be  only  a 
limited  development  of  mycelial  filaments,  —  not  as  much  as 
may  often  be  found  in  badly  seasoned  logs.    This  condition  of 
preservation  is  to  be  ascribed  chiefly,  no  doubt,  to  the  fact  that 
the  wood  was  hermetically  sealed  in  an  impervious  cby  which 
completely  excluded  all  fungi  and  inhibited  further  growth  of 
those  originally  present.    This  explanation  appears  the  more 
probable  from  the  fact  that  leaves  of  the  Vallisneria  spiralis, 
embedded  in  the  same  clays,  show  all  the  details  of  the  original 
structure  when  freshly  exposed,  and  it  is  only  upon  subsequent 
dessication  that  disorganization  takes  place. 

Juniperus  californica  from  the  interglacial  deposits  of  Hum- 
boldt County,  California  (46),  offers  a  very  similar  though  much 
more  instructive  example  of  preservation  through  long  periods 
of  time.    This  wood  was  obtained  from  two  localities,  in  the  one 
case  occurring  in  blue,  sandy  silt  under  one  hundred  and  fifty 
feet  of  local  debris,  while  in  the  other  case  it  was  embedded 
in  blue,  slaty  muck  under  fifty  to  sixty  feet  of  local  debris.    A 
microscopic  examination  showed  that  the  structure  contains  very 
few  mycelial  filaments,  in  fact  only  slightly  more  than  in  the 
Don  specimen  of  Juniperus  virginiana.    The  structure  of  the 
tissues  is  well  preser\ed  and  gives  no  evidence  of  that  oblitera- 
tion of  parts  which  usually  accompanies  the  operation  of  fungi 
and  bacteria,  whence  we  may  correctly  infer  that  such  organisms 
were  not  operative.    It  was  nevertheless  found  that  the  tissues 
did  not  offer  the  normal  amount  of  resistance  to  the  action  of  the 
knife  in  cutting  sections,  the  result  being  a  localized  fragmenta- 
tion.   The  material  was  only  very  slightly  silicified  and  there  was 
no  difficulty  in  the  removal  of  the  mineral  matter,  but  the  entire 
structure  presented  unusual  thickening  of  the  cell  walls,  such 
as  would  arise  through  the  action  of  strong  alkali.    Alterations 
of  this  character  are  not  infrequent  among  fossil  plants,  most 


1 66 


ANATOMY  OF  THE  GYMNOSPERMS 


particularly  among  those  which  are  eventually  silicified,  and  in 
the  present  instance  they  serve  to  explain  the  mechanical  weak- 
ness of  the  tissue,  the  cellulose  substance  of  which  has  undergone 
a  gradual  molecular  alteration  consequent  upon  the  action  of  an 
alkaline  solution  —  possibly  of  a  hot  spring  —  which  has  been 
continued  indefinitely. 

The  Douglas  fir  is  regarded  as  one  of  the  most  durable  of 
woods,  and  it  is  not  surprising  to  find  instances  of  its  perfect 
preservation  under  very  adverse  circumstances.    Specimens  of 
Pseudotsuga  macrocarpa,  from  the  same  beds  as  the  Californian 
juniper  already  described,  exhibit  the  same  absence  of  special 
silicification,  but  they  differ  in  a  much  more  marked  development 
of  fungus  mycelia,  and  in  a  .somewhat  extreme  alteration  through 
the  action  of  free  alkali,  which  has  been  carried  so  far  that  in  the 
summer  wood  the  cell   cavities  are  largely  obliterated,  while 
the  thinner-walled  tissue  of  the  spring  wood  shows  definite  col- 
lapse.   Apart  from  this  there  is  no  evidence  of  the  removal  of 
parts  through  the  action  of  decay,  and  we  may  conclude  that 
the  fungus  present  had  not  produced  any  specific  effect.    Yet 
another  illustration  is  afforded  by  Pseudotsuga  Douglasii  from 
Mystic  Lake  at  Bozeman,  Montana,  where  it  was  found  under 
eight  feet  of  the  old  lake-bed  deposit,  which  antedates  a  well- 
defined  and  superimposed  gl  cial  deposit.    The  age  of  this  for- 
mation is  open  to  discussion,  as  it  may  represent  local  glaciation 
of  recent  date,  while  there  is  al.so  a  possibility  that  it  may  be 
synchronous  with  the  continental  interglacial  period,  since  the 
absence  of  the  tree  from  the  same  locality  at  the  present  day 
leads  us  to  suppose  that  its  removal  occurred  in  the  time  of 
general  glaciation,  as  may  be  inferred  from  other  evidence  (46). 
In  its  external  aspects  the  wood  presents  a  remarkably  perfect 
state  of  preservation,  exhibiting  all  the  features  of  grain  and 
other  structural  details,  even  to  an  exhibition  of  the  bordered 
pit?  which  may  be  readily  determined  with  a  hand  lens  of  mod- 
erate power.    Furthermore  it  was  wholly  free  from  infiltrated 
mineral  matter  and  was  readily  softened  in  boiling  water  so  that 
sections  could  be  cut  with  the  greatest  ease.    Internally  the 


DURABILITY  OF  WOODS 


167 


detail  .  showing  no  evdence,  of  decay  and  a  remarkable  freedom 
from  fungus  mycelia,  from  which  we  may  conclude  tha!  he  tree 
was  not  only  buried  but  practically  hermetically  sealed  up  1 
,x,ss.bly  by  the  operation  of  an  avalanche  -  beLe  an  oppor- 
tumty  for  the  action  of  fungi  and  the  operations  of  deca^^'. 

The  genus  Picea  is  a  widely  distributed  type  in  the  Pleistocene 
deports,  i^rfcularly  in  Canada.    A  large  amount  of  materL 
has  been  obtamed  from  the  Pleistocene  clays  of  the  Don  valW 
at  Toronto  and  elsewhere,  and  it  affords  an  excellent  index  o^ 
the  durab.hty  of  the  wood  under  such  conditions.    AH  of  the 
matenal  has  been  found  to  be  devoid  of  silicification  or  other 
mmeraluation.  and  it  presents  somewhat  diversified  aspects  with 
respect  to  conditions  of  preservation.    P.  alba,  of  the  S  IrC 
oush  period,  although  the  wood  is  fairly  well  preserved  ifa 
whole  and  readily  admits  of  a  determination  of  the  species  shows 
a  grea    abundance  of  fungus  mycelia.    Wherever  this  i^  to  be 
found  there  ,s  a  marked  alteration  in  the  structure  of  the  cell 
wall,  mvolvmg  a  breaking  down  of  the  secondary  layer,  as  usu 

LTIT  ?T'  ^•«^"'"^^--^'  ^•^'•^  disintegration  being 
ahvays  most  marked  m  those  regions  where  the  mycelium  is 
most  abundant.  In  this  case  the  relation  of  the  fungus  to  the 
changes  noted  is  very  obvious. 

J!^'^'^'^''  ^'■°'"  '^'  ^°"  '^^P''^'^^  '^  •"  '^^^  ^^«es  so  well 
preserred  as  to  permit  of  a  determination  of  the  species  with- 
out difficulty,  while  in  other  cases  the  decay  has  progress  J  so 
far  as  to  render  identification  impossible.  Fungus  m^  hf  a " 
-ys  present  and  they  clearly  constitute  the  active  agen 

Itr;  7      ""'^^^  ''^^'""^  "'"'"^'""^  °f  preservation  here 

ZtT  r^^T  """  "^''■"'•°"  "^  ^J'^^'fi*-^  ^^"«^«  wholly 
P  t  om  the  mherent  qualities  of  durability  which  the  wood 
aturally  possesses.  These  are  to  be  sought  for  in  two  direc- 
tions, either  ,n  local  conditions  of  preservation,  as  varying 
permcabihty  of  the  soil,  or  in  the  conditions  of  decay  established 
Pr.ur  to  entombment.    All  of  the  material  has  been  derived  from 


M"-': 
i 

ft 


*9mi 


I'L 


1 68 


ANATOMY  OF  THE  (iYMNOSPERMS 


a  compact  clay,  which  offers  a  practically  air-tight  matrix  of 
essentially  the  same  physical  character  in  all  cases.  It  therefore 
seems  improbable  that  local  variations  of  the  inclosing  material 
could  have  been  so  different  as  to  give  rise  to  the  diverse  aspects 
of  decay  noted,  though  such  may  have  been  a  factor  of  secondary 
importance.  The  fact  that  under  essentially  the  same  conditions 
some  specimens  were  well  preserved  while  others  were  badly 
decayed,  at  once  directs  attention  to  the  probable  operation  of 
antecedent  causes.  It  is  quite  obvious  that  trees  which  eventu- 
ally become  fossilized  are  neither  of  the  same  age  when  they  fall 
nor  are  they  in  the  same  condition  of  soundness.  Some  may  be 
quite  sound,  while  others  may  be  infested  with  fungi,  and  the  living 
tree  may  therefore  present  the  somewhat  advanced  progress  of 
decay.  But  the  fossils  of  the  Don  deposits  are  obviously  fragments 
of  trees  which  had  been  brought,  through  the  agency  of  water,  to 
the  places  where  found,  and  it  is  quite  clear  that  while  some  of  the 
trees  may  have  been  speedily  buried  others  were  no  doubt  a 
long  time  in  the  water  before  being  inclosed  in  the  sedimentary 
deposits.  Decay  would  have  an  opportunity  for  extended  devel- 
opment under  such  conditions,  and  it  would  even  continue  for 
an  indefinite  period  after  entombment.  On  the  other  hand,  the 
rapid  entombment  of  a  vigorous  tree  in  which  decay  had  not 
yet  made  its  appearance  might  involve  the  inhibition  of  fungoid 
growth.  On  this  hypothesis,  which  seems  to  present  the  prefer- 
able alternative,  it  is  possible  to  satisfactorily  account  for  the 
varied  states  of  preservation  noted,  as  arising  under  essentially 
uniform  conditions. 

The  common  larch  (Larix  americana)  is  another  wood  of  very 
widespread  occurrence  throughout  the  Pleistocene  depo.sits.  Two 
widely  separated  localities  may  be  selected  as  afJordin-  exam- 
ple' its  preser  ition.  At  Dahlonega,  Georgia,  this  species  has 
been  found  in  the  black  clays,  which  are  to  be  regarded  as  prob- 
ably synchronous  with  and  equivalent  to  the  Pleistocene  deposits 
of  more  northern  localities  (51).  The  material  was  found  to  be 
wholly  free  from  impregnation  with  mineral  matter,  but  it  exhib- 
ited the  somewhat  extreme  effects  of  advanced  decay  with  the 


DURABILITY  OF  WOODS 


169 


subsequent  operation  of  pressure.'  so  that  it  was  with  some  diffi- 
culty that   sections  were  made  which  would  show  structure 
The  entire  structure  showed  abundant  fungus  mycelia,  while 
the  walls  of  the  tracheids  had  suffered  such  reduction  under  the 
operation  of  decay  that  the  secondary  walls  were  largely  removed 
with  a  corresponding  obliteration  of  structural  markings,  and  the 
whole  fabric  was  reduced  to  a  compressed  and  greatly  modified 
skeleton  consisting  of  the  primary  cell  walls.    Numerous  speci- 
mens  from  the  Don  valley  show  that  while  some  are  full  of  fun- 
gus  hyphae  and  present  a  correspondingly  advanced  state  of  decay 
others  from  precisely  the  same  locality  show  a  total  absence  of 
all  fungoid  growths  and  a  completeness  of  structural  details 
which  leaves  nothing  to  be  desired  by  way  of  comparison  with 
recently  cut  material.    Here  it  is  still  more  evident  that  the 
explanation  applied  to  Picea  nigra  is  not  only  applicable  in  this 
case  also,  but  that  it  affords  a  correct  insight  into  the  reason 
for  the  various  conditions  of  preservation  of  wood  which,  when 
embedded  m  clay,  is  practically  imperishable.    A  more  recent 
example  of  the  larch  may  serve  to  lend  emphasis  to  these  con- 
clusions, and  It  is  of  particular  interest  because  it  embodies  the 
changes  which  may  arise  in  the  course  of  practical  use.    In  the 
Peter  Redpath  Museum  of  McGill  College  there  is  a  specimen 
of  an  old  aqueduct  log  which  was  laid  down  in  the  early  days  of 
Montreal.    The  old  and  long-forgotten  pipes  were  uncovered  in 
the  course  of  excavations  for  a  new  water  main  on  St.  Paul 
Street.    They  were  about  one  foot  in  diameter,  with  a  two-inch 
bore.    According  to  a  communication  in  one  of  the  daily  papers 
the  pipes  were  laid  about  eighty  years  previous,  but  were  in 
use  for  only  a  short  time.    An  examination  showed  that  when 
the  pipes  were  recovered  they  were  practically  sound,  with  the 
exception  of  the  superficial  layers,  which  had  so  far  yielded  to 
decay  as  to  be  in  process  of  removal,  and  the  external  form  had 
thereby  suffered  some  alteration.    A  microscopic  examination 
showed  the  structure  to  be  so  perfectly  preserved  as  to  admit  of 

'Recent  studies  indicate  that  the  amount  of  pressure  required  to  produce 
uch  results  need  not  be  very  great,  probably  less  than  one  hundred  pounds. 


It 


170 


ANATOMY  OK  THE  GVMNOSIMRMS 


klentificution  without  any  <|iiesfion,  and  there  was  Init  slight  evi- 
dence of  the  operation  of  decay,  a  fnct  which  goes  far  to  support 
the  hypothesis  already  di?»i  ussed,  that  if  the  wood  is  sound  when 
buritil  II)  a  compiut  and  air-tiglit  matrix,  its  decay  depends 
essentially  upon  that  which  had  been  initiated  before  inclosure, 
and  that  otherwise  there  is  essentially  no  change. 

Upon  assuming  c^^arge  of  the  office  of  governor  of  Montreal 
in  1642,  Maisonncuve  constnaed  a  palisaded  fort  near  'he 
present  location  of  the  customhouse.  In  1890,  in  the  course- 
of  excavations  in  that  locality,  the  workmen  uncovered  hewn 
timbers  which  were  held  to  represent  a  portion  of  the  palisade 
of  the  old  fort.  A  specimen  ot  one  of  these  may  now  be  seen 
in  the  museum  of  the  Natural  History  Society  of  Montreal.  It 
represents  the  wood  ot  the  common  red  pine  (Pinus  resinosa). 
E.Nternally  the  wood  has  all  the  aspects  of  a  recently  cut  log,  a 
state  of  preservation  which  is  amply  support etl  by  microscopical 
examination,  from  which  we  learn  that  there  is  very  little  myce- 
lium present,  and  that  the  structure  is  as  perfect  as  if  taken 
from  a  tree  of  present  growth,  notwithstanding  its  probable 
burial  for  two  and  one-half  centuries. 

Data  of  a  more  recent  character  with  respect  to  the  duration 
of  timbers  used  for  constructive  purposes  may  be  derived  from 
actual  experience.  Thus  Dudley  has  found  that  when  the  yellow- 
pine  (Pinus  palustris)  is  employed  in  the  ground  or  used  as  tics, 
it  very  quickly  decays,  being  destroyed  by  the  action  of  Len- 
tinus  lepideus,  Fr.,  although  the  wood  is  very  durable  under 
conditions  of  comparative  dryness  (14).  In  the  case  of  tics  from 
the  Panama  railway,  he  also  points  out  that  they  were  useless 
in  two  years,  while  similar  ties  employed  in  the  southern  states 
lasted  from  four  to  six  years,  and  in  the  middle  states  they 
lasted  from  five  to  eight  years,  showing  very  clearly  the  influ- 
ence of  varying  climatic  conditions,  particularly  with  respect  to 
the  relative  humidity  and  temperature.  According  to  the  same 
authority,  cedar  ties  (Cupressus  thyoides)  will  last  from  eight 
to  ten  years,  even  when  not  wholly  sound  at  the  time  of  layin;:, 
while  hemlock  ties  (Tsuga  canadensis)  have  a  life  of  only  four 


DURABILITY  OF  WOODS  ,., 

yiars.  The  relation  of  special  conditions  of  moisture  is  further 
exhibited  in  these  cases  in  the  fact  that  ties  which  were  perfectly 
sound  on  the  exposed  sides  are  very  often  found  to  be  in  an 
advanced  state  of  decay  throuKh.nit  the  buried  parts.  Mutilation 
IS  an  important  factor  in  the  introduction  of  decay,  and  Dudley 
has  shown  (U)  that  where  spikes  have  been  driven  into  the  ties 
and  where  the  structure  has  thereby  suffered  mechanical  altera- 
tion,  decay  finds  an  opportunity  for  speedy  entrance  into  the 
interior  tissues,  which  it  rapidly  permeates  and  destroys.  This 
relation  of  cause  and  effect  is  in  perfect  harmony  with  what 
has  long  been  known  to  occur  in  living  trees  where  broken  or 
badly  amputated  limbs  afford  an  opportunity  for  fungi  to  pene- 
trate and  destroy  otherwise  healthy  tissues. 

The  preceding  considerations  have  directed  attention  to  the 
fact  that  coniferous  woods  may  be  preserved  indefinitely,  pro- 
vided they  are  completely  excluded  from  fresh  supplies  of  free 
oxygen  and  are  maintained  under  conditions  of  low  tempera- 
ture.—in  other  words,  hermetically  sealed  in  an  impervious 
medium.    While  we  are  thus  in  a  position  to  understand  the 
conditions  under  which  a  very  large  proportion  of  woods  are 
preserved  as  fossils  in  the  more  recent  geological  strata,  no 
explanation  is  offered  which  will  adequately  account  for  the 
mode  of  preservation  of  the  large  number  of  plants  met  with 
m  the  older  rocks,  even  as  far  back  as  the  Devonian  and 
Silurian,  and  it  is  desirable  that  examples  of  these  should  be 
passed  in  review.    In  this  connection  four  principal  forms  of 
preservation  may  be  noted. -(,)  carbonization,  (2)  silicification, 
(3)  calcification,  and  (4)  pyritization. 

Carbonhadon.  This  form  of  preservation  is  essentially  char- 
acteristic of  plants  derived  from  the  coal  measures,  and  it  is 
represented  by  coal  itself.  It  depends  essentially  upon  a  gradual 
withdrawal  of  the  elements  of  water  from  the  original  cellulose 
■substance,  whereby  a  relative  excess  of  carbon  is  developed.  It 
's  a  change  which  takes  place  under  exclusion  of  air,  and  it  is 
no  doubt  facilitated  by  the  action  of  heat  and  possibly  also  of 
pressure.    It  is  obvious,  however,  from  the  nature  of  the  changes 


MICROCOPY   MSOIUTION   TIST  CHART 

(ANSI  and  ISO  TEST  CHART  No.  2) 


^  APPLIED  IN/MGE     Inc 

=;  1653  East  Main   Stre»l 

r^  Rochester.   New  York        U609       USA 

^=  (716)  482  -  0300  -  Phone 

^S  (716)   2U  -  S989  -  FoK 


172 


ANATOMY  OF  THE  GYMNOSPERMS 


involved,  that  they  not  only  proceed  very  slowly,  but  that  it  is 
possible  to  find  plant  remains  which  present  different  stages  of 
the  process,  as  represented  by  the  various  forms  of  peat,  brown 
coal,  soft  coal,  and  anthracite.    Being  determined  by  the  with- 
drawal of  hydrogen  and  oxygen  from  the  original  tissues,  these 
alterations  must  arise  very  unequally  in  different  parts  of  the 
plant  body,  as  determined  by  the  character  of  the  tissue  involved 
and  the  relative  percentage  of  carbon  originally  present  in  the 
cellulose  substance.    In  the  progress  of  such  changes,  gases 
constitute  some  of  the  most   abundant  and  conspicuous  end 
products.    While  under  ordinary  circumstances  they  may  be  lib- 
erated continuously,  they  may  be  stored  under  favorable  condi- 
tions, to  be  liberated  in  great  volume  at  a  later  period.    Thus 
it  has  been  shown,  as  the  result  of  recent  observations  (88), 
that  where  plant  remains  accumulate  in  large  quantities,  sul- 
phureted   hydrogen   together   with    the   light   carbureted  and 
phosphureted  hydrogen  arise.    The  two  latter,  being  subject 
to   spontaneous    combustion,   take  fire  upon  coming  in   con- 
tact with  the  air,  and,  setting  fire  to  the  associated  sulphureted 
hydrogen,  an  extensive  conflagration  may  result.    Phenomena  of 
this  kind  on  a  large  scale  rarely  come  within  the  observation  of 
man,  but  that  such  have  been  observed  affords  abundant  ground 
for  the  belief  that  many  foiest  fires  of  obscure  origin  are  to  be 
accounted  for  in  this  way.    Thus,  once  more  comparing  the  per- 
centage composition  of  the  principal  cellulose  modifications,  it 
is  found  that  normal  cellulose  contains  44  per  cent  of  carbon, 
lignin  _bout  62  per  cent,  while  cork  contains  upwards  of  74  per 
cent.    In  accordance  with  this  principle  it  will  be  found  that 
wood  tissue  becomes  carbonized  sooner  than  the  softer  parts  of 
the  structure,  which  may  already  have  disappeared  through  the 
operation  of  decay,  or  the  highly  carbonaceous  cork  tissue  of 
the  bark  may  be  converted  into  a  structureless  mass  of  carbon, 
while  yet  the  less  carbonaceous  wood  tissue  is  preserved  in  all 
its  details.    It  is  thus  possible,  in  a  silicified  wood,  to  recognize 
and  define  .he  general  limits  of  the  bark  by  the  carbonized  layer 
which  oftentimes  forms  the  outer  portion  of  a  fossil  wood. 


j  i 


DURABILITY  OF  WOODS  ,73 

Carbonization  necessarily  involves  a  more  or  less  profound 
obliteration  of  structural  detaUs.    This  is  especially  true  in  those 
cases  in  which  an  absence  of  infiltrated  mineral  matter  has  pre- 
vented a  retention  of  the  original  structural  details,  and  where 
pressure  m  conjunction  with   heat,  as  in  hard  coal,  has  pro- 
duced a  secondary  effect.    From  this  point  of  view  it  is  true 
that  a  highly  carbonized  cortex  rarely  presents  any  structural 
details.    Lignites  and  some  of  the  softer  coals  not  infrequently 
present  welWefined  structure,  but  the  same  cannot  be  expected 
of  the  hard  coals,  in  which  extreme  alteration  has  been  effected 
In  many  cases,  such  as  may  be  found  in  the  Devonian  and  later 
formations,  carbonization  is  joined  to  silicification  or  calcification 
and  gives  rise  to  resultant  forms  of  preservation,  which  will  be 
discussed  more  fully  and  with  more  propriety  in  the  next  chapter- 
but  attention  may  be  directed  to  the  general  fact  that  where 
carbonization  operates  by  itself  the  fossil  acquires  an  opacity 
which  renders  it  very  difficult  to  determine  details,  while  the 
structure  also  becomes  so  friable  as  to  make  special  methods  of 
section  cutting  imperative. 

Silicification.  Thij  is  by  far  the  most  common  form  in  which 
the  stems  of  plants  are  preserved  in  the  older  rocks.  It  depends 
upon  the  slow  infiltration  of  a  solution  of  an  alkaline  silicate  into 
the  tissues,  whereby  the  entire  structure  eventually  becomes  con- 
verted into  a  mass  of  silica,  as  in  the  trees  of  the  petrified  for- 
ests of  Arizona,  or  as  may  be  seen  in  some  of  the  larger  alga; 
such  as  Nematophycus  from  the  Devonian.  According  to  the 
rate  of  infiltration,  relatively  to  the  operation  of  decay,  all  struc- 
tural details  may  be  observed.  Under  ordinary  circumstances, 
however,  such  a  method  of  preservation  is  one  of  the  most 
advantageous  for  the  purposes  of  scientific  study,  because  of 
the  transparency  of  the  mass  and  the  permanent  form  of  the 
material. 

Calcification.  This  form  of  mineralization  is  much  less  com- 
mon than  silicification,  with  which  it  may  be  combined.  In 
some  cases,  however,  calcite  constitutes  the  entire  mass  of  the 
mfiltrated  material,  as  in  the  case  of  Osmundites  skidegatcnsis 


174 


ANATOMY  OF  THE  GYMNOSPERMS 


from  the  Cretaceous  of  the  Queen  Charlotte  Islands,  which,  as 
shown  on  a  former  occasion  (56),  contains  at  least  70  per  cent 
of  calcium  carbonate.  The  general  effect  of  this  form  of  pres- 
ervation upon  the  structure  is  substantially  the  same  as  in 
silicification. 

Pyrithation.  A  still  less  common  form  of  preservation  is  that 
which  involves  a  replacement  of  the  silica  or  calcite  of  the  pre- 
vious forms  by  crystalline  sulphide  of  iron.  This  is  a  feature 
more  or  less  common  to  fossils  from  the  older  formations,  which 
always  involves  a  complete  obliteration  of  structural  details, 
though  in  rare  cases  the  more  general  features  may  be  seen 
when  viewed  by  reflected  light.  Plants  presenting  this  form 
of  preservation  are  among  the  least  val  able  for  purposes  of 
scientific  study. 


CHAPTER  XIII 

DECAY :  ITS  MODE  OF  ACTION  AND  EFFECTS 

In  discussing  the  operation  of  decay  in  the  woody  tissue  of 
a  stem,  it  will  be  desirable  to  have  reference  to  (i)  the  nature 
of  the  active  agents,  (2)  the  conditions  under  which  they  flour- 
ish, (3)  their  mode  of  operation,  and  (4)  their  effects  upon  the 
structure  and  mode  of  preservation. 

I.  T/te  nature  of  the  active  agents.  Decay  has  its  origin  in  the 
growth  of  certain  plants  of  a  low  degree  of  organization,  which, 
through  their  ability  to  seek  food  supplies  either  in  living  or 
dead  organic  bodies,  produce  such  an  unusual  course  of  develop- 
ment as  to  effect  an  actual  disorganization  of  the  tissues,  as 
expressed  in  decay.  To  understand  fully  the  nature  and  mode 
of  operation  of  these  plants,  it  will  be  necessary  to  briefly  pass 
in  review  their  essential  characteristics. 

'imong  the  lower  forms  of  plants  we  recognize  two  somewhat 
nearly  related  groups,  which  present  many  features  in  common, 
both  with  respect  to  their  influence  upon  the  promotion  of  dis- 
ease and  decay  and  to  their  general  habits  of  life,  but  which 
nevertheless  differ  very  materially  in  their  structure  and  the 
details  of  their  life  history.  The  first  group  embraces  what  are 
known  as  the  Bacteria,  —  plants  characterized  by  their  unicel- 
lular structure,  which  rarely  assumes  a  filamentous  form,  and 
by  the  fact  that  while  they  may  and  frequently  do  propagate 
through  the  medium  of  spores,  they  more  commonly  multiply 
by  simple  fission,  in  consequence  of  which  they  are  designated 
the  fission  fungi  or  Schizoniycctcs.  Their  life  history  is  very 
simple,  and  the  incomplete  cycle,  which  is  wholly  devoid  of  a 
se.xual  phase,  is  repeated  at  very  frequent  intervals,  so  that  they 
multiply  with  enormous  rapidity.  The  nutrition  of  the  bacteria 
IS  derived  by  a  process  of  direct  absorption  from  the  surrounding 

•7S 


:f 


% 


176 


ANATOM\   OF  THE  GYMNOSPERMS 


medium  without  the  development  of  specialized  organs  for  that 
purpose.    Owing  to  their  minute  size  they  are  readily  distrib- 
uted by  even  slight  currents  of  air,  from  which  they  eventually 
settle  as  constituents  of  dust.    Their  spores  offer  a  remarkable 
degree  of  resistance  to  ordinary  conditions,  whereby  they  may 
survive  a  most  adverse  environment  for  prolonged  periods,  and 
again  produce  the  vegetative  form  when  favorable  conditions 
are  once  more  established.    It     ill  thus  be  observed  that  the 
growth  and  operation  of  such  plants  is  not  necessarily  continu- 
ous, but  that  their  action  may  be  intermittent  or  periodic,  as 
determined  by  the  special  circumstances  under  which  they  are 
placed.    In  any  event,  the  characteristics  noted  favor,  in  an 
exceptionally  high  degree,  the  wide  prevalent-  of  the  effects  of 
which  they  are  the  immediate  cause.    It  wouiu  be  out  of  place 
here  to  enter  upon  a  detailed  discussion  of  these  effects,  and  it 
will  suffice  to  direct  attention  to  the  very  general  relation  of 
these  plants  to  the  production  of  disease  in  both  plants  and 
animals,  while  their  relation  to  the  disorganization  of  organic  tis- 
sues is  exemplified  in  the  various  processes  of  maceration  which 
constitute  so  essential  a  feature  in  many  important  industrial 
processes. 

The  second  group  of  plants  includes  the  Fungi,  —  plants 
distinguished  by  their  somewhat  higher  degree  of  organization 
and  the  development  of  specialized  organs.    They  are  generally 
multicellular,  and  the  pjant  body,  or  mycelium,  is  in  the  form  of 
a  septate,  or  nonseptate  and  branching,  microscopic  filament, 
which  is  capable  of  very  rapid  extension,  and  which  may  also 
brmg  about  a  vegetative  propagation  by  simple  subdivision.    At 
certain  stages  of  its  growth,  as  also  under  special  conditions  of 
moisture  and  temperature,  the  mycelium  gives  rise  to  asexual 
reproductive  bodies,  or  spores.    Such  spores  are  very  minute, 
and  are  composed  each  of  a  single  cell.    They  may  or  may  not 
arise  through  the  medium  of  a  sexual  process,  the  fungi  exhibit- 
mg  a  great  diversity  in  this  respect,  a  discussion  of  which  is 
unnecessary  at  this  time.    The  spores  are  generally  produced 
m  vast  numbers  ;  they  are  most  readily  distributed  by  the  wind 


DECAY 


177 


or  even  by  slight  movements  of  the  air;  their  extreme  buoy- 
ancy  keeps   them  afloat   for   prolonged  periods,  though  they 
eventually  settle  as  one  of  the  ordinary  constituents  of  dust ; 
they  offer  a  high  degree  of  resistance  to  deleterious  influences,' 
and  are  thus  capable  of  bridging  over  critical  periods,  at  the  end 
of  which  they  may  germinate  with  great  freedom.    It  will  thus 
be  seen  that  through  such  spores  it  is  possible  /or  the  fungi  to 
develop  wherever  and  whenever  favorable  conditions  are  met 
with.    The  life  history  of  the  fungi  is  usually  much  longer  and 
more  complex  than  that  of  the  bacteria,  and  while  the  life  cycle 
often  involves  both  a  sexual  and  an  asex-.al  phase,  the  former 
may  not  appear  throughout  a  very  much  prolonged  period  of 
development,  within  which  the  plant  may  nevertheless  extend 
with  great  rapidity  and  produce  all  the  characteristic  effects 
of  its  growth. 

Both  the  bacteria  and  the  fungi  are  characterized  by  the  ab- 
sence of  a  green  pigment,  or  chlorophyll,  and  their  consequent 
inability  to  produce  carbon  compounds  from  the  carbon  dioxide 
of  the  atmosphere  as  a  source  of  energy.    With  the  exception  of 
a  few  of  the  bacteria,  the  energy  of  aU  these  plants  depends 
entirely  upon   the  oxidation  of  carbon  compounds  previously 
formed  and  accumulated  by  some  other  organisms,  primarily 
those  which  contain  chlorophyll.    It  is  therefore  imperative  that 
such  compounds  should  be  derived  directly  from  the  nutrient 
fluids  of  a  living  organism,  or  host,  upon  which  the  parasite 
feeds ;  or  that  it  should  be  obtained  as  one  of  the  product^  of  a 
decay  induced  by  the  fungus  or  bacillMs  which  thereby  becomes 
a  saprophyte.    From  the  naure  of  their  process  of  nutrition, 
saprophytes  are  generally  found  within  the  body  upon  which 
they  act,  and  they  are  thus  endophytic.    This  is  particularly 
true  of  the  bacteria.    The  more  highly  organized  fungi  may 
live  chiefly  upon  the  surface  of  the  body  (epiphytic),  sending 
the  branches  of  their  mycelium  (the  hyphce)  into  the  interior 
parts,  where  they  develop  spetiali.red  feeding  branches  {haus- 
toria),  which  arise  wherever  food  supplies  are  to  be  met  with. 
Or,  again,  endophytic  forms  may  reach  the  surface  only  at  certain 


•78 


ANATOMY  OK  THE  GYMNOSPERMS 


periods  of  development  a  .nder  special  conditions  of  environ- 
ment,  when  they  become  recognizable  without  the  aid  of  the 
microscope  by  reason  of  their  characteristic  fruiting  structures. 
It  is  further  true  that  in  these  two  groups  of  plants  there  is 
a  more  or  less  variable  relation  toward  the  source  of  food  supply. 
This  is  expressed  by  the  classification  long  since  adopted  by 
De  Bary  (83),  and  now  generally  used  with  slight  modifica- 
tions, who  recognized : 

1.  True  or  obligate  saprophytes:  those  which  obtain  their  food  supplies 
from  the  products  of  organic  decay  under  all  circumstances. 

2.  Partial  ox  facultative  saprophytes :  those  which  u.sually  complete  the 
life  cycle  as  true  saprophytes,  but  which,  under  special  circumstances,  may 
more  or  less  completely  but  temporarily  become  parasites. 

3-  True  or  obligate  parasites :  plants  which  invariably  derive  their  nutri- 
tion directly  from  the  nutritive  materials  of  living  organisms. 

4.  Partial  ox  facultative  para.sites:  those  which,  under  .special  circum- 
stance.s,  may  become  saprophytes,  though  ordinarily  completing  the  life 
cycle  as  true  parasites. 

Among  the  very  large  number  of  parasites  and  saprophytes 
which  attack  timber,  either  living  or  dead,  it  will  be  found  that 
within  certain  limits  there  is  a  more  or  less  well-defined  relation 
to  ti.e  organism  affected,  whereby  it  is  characterized  by  the 
growth  of  special  forms.    The  number  of  species  peculiar  to  a 
given  tree  will  be  found  to  vary  somewhat  widely,  and  this  will 
in  turn  be  influenced  within  the  limits  of  a  particular  species  of 
tree  by  conditions  of  environment.   Thus  \on  Schrenk  (68,  49) 
shows  that  the  wood  of  Catalpa  specio.sa  is  injuriously  affected 
by  only  two  fungi,  and  the  same  is  likewise  true  of  the  red  cedar 
(Juniperus  virginiana);  but  Dudley  (14)  points  to  the  fact  that 
no  less  than  eighteen  species  of  fungi  infest  the  wood  of  the 
hemlock  (Tsuga  canadensis),  of  which  nine  are  Polypori  and  six- 
Agarics.    Again,  it  is  a  well-known  fact  that  other  fungi,  such  as 
dry  rot  (Merulius  lachrymans),  are  not  selective  in  any  particu- 
lar sense,  but  by  reason  of  their  very  cosmopolitan  habits  they 
grow  within  any  wood,  provided  the  external  conditions  of  warmtli 
and  moisture  are  favorable.    It  by  no  means  follows  from  the 


DECAY 


»79 


above  statement  that  all  the  fungi  found  in  a  particular  wckkI 
either  produce  the  same  or  even  similar  diseases,  that  they  are 
equally  active,  or  that  they  operate  under  all  conditions ;  and  it 
will  suffice  m  this  connection  to  again  direct  attention  to  the 
results  obtained  by  von  Schrenk  in  the  case  of  the  hardy  Catalpa, 
with  respect  to  which  he  shows  that  soft  rot  produced  by  Polv 
porus  versicolor  (L.).  Fr..  rapidly  destroys  the  heartw„od.  while 
the  brown  rot  induced  by  Polyporus  catalp.x.  von  Schr..  operates 
throughout  the  trunk  near  its  base ;  and  yet  again,  while  these 
two  diseases  produce  specific  and  distinct  effects  in  the  living 
tree  (68).  there  is  as  yet  no  fungus  known  which  will  grow  in 
the  tissue  of  the  catalpa  wood  after  it  has  been  cut  and  dried.— 
a  fact  which  readily  explains  the  remarkable  durability  of  this 
wood  and  its  adaptation  to  purposes  where  freedom  from  decay 
IS  a  first  consideration. 

2.  Conditions  under  -.vUich  they  flourish.  In  entering  upon  a 
discussion  of  the  conditions  under  which  fungi  operate  in  plant 
tissues,  we  must  assume,  as  is  in  reality  true  in  all  cases,  that 
the  latter  contain  an  appreciable  amount  of  material  which  may 
be  utilized  by  the  fungus  for  the  purposes  of  its  own  nutrition 
Such  food  material  is  always  presented  by  the  cellulose  sub- 
stance of  the  cell  wall,  which  is  thereby  broken  down  and  grad- 
ually removed,  though  this  does  not  occur  usually  until  other 
and  more  available  forms  of  food  material  have  been  exhausted. 

'      econd  place,  the  nutrient  material  stored  by  the  plant 
wn  sustenance,  such  as  the  starches  and  sugars,  are 
-  attacked  by  fungi,  and  so  long  as  they  last  the  invading 

■.  „..nism  confines  its  operations  chiefly  to  those  regions  and 
particular  cells  in  which  such  storage  is  most  marked.  Apart 
from  such  conditions  of  food  supply,  which  must  be  held  to  be 
of  fundamental  importance  and  to  be  a  constant  factor  under 
all  circumstances,  air,  temperature,  and  moisture  must  also  be 
regarded  as  essential  though  variable  factors  which  operate  as 
the  real  determinants  in  the  growth  of  the  invading  organism 

The  active  growth  of  all  plants  demands  an  abundant  supplv 
of  oxygen.    In  the  vast  majority  of  cases  this  gas  is  derived 


i8o 


ANAIOMV  OF  THK  (lYMNOSPERMS 


directly  from  the  air,  or  indirectly  throii^'h  the  medium  of  the 
surrounding  fluid,  such  as  water,  in  which  the  oiganism  may  be 
growing.    Such  aerobes  cannot  exist  when  the  supply  of  oxy- 
gen from  cither  of  the  sources  indicated  is  cut  off,  since  their 
resi)iratory  function   is   inhibited   and  all  dependent   activities 
necessarily  cease.    It  is  true  tlat  some  plants,  such  as  certain  of 
the  bacteric ,  cannot  live  under  such  conditions  of  free  aeration,  in- 
asmuch as  ihey  have  become  adapted  to  obtaining  their  oxygen 
from  the  products  of  organic  decomposition,  and  any  access  of 
air  or  free  oxygen  at  once  inhibits  their  growth.    Such  anaerobes 
form  a  comparatively  small  but  none  the  less  exceedingly  im- 
portant group  of  plants,  and  it  is  a  knowledge  of  these  differences 
in  the  life  history  of  the  organism  which  enables  us  to  gain  an 
intelligent  insight  into  the  operation  of  the  various  forms  of 
organic  decay.    It  may  be  stated,  then,  that  the  fungi  in  general 
cannot  grow  exce-  ♦  under  conditions  which  afTord  a  free  supply 
of  oxygen,  and  this  fact  supplies  t'  c  basic  principle  on  which  to 
found  methods  for  retarding  or  permanently  arresting  the  oper- 
ation of  fungi.    But  it  will  be  found  in  practi«.»  that   this  is 
further  dependent  upon  the  remaining  factors  of  warmth  and 
moisture.    In  the  preceding  chapter  it  has  been  shown  that  the 
spores  of  fungi,  as  also  those  of  the  bacteria,  are  capable  of  enter- 
ing upon  a  resting  state  whereby  they  become  capable  of  resist- 
ing very  adverse  influences,  but  that  they  are  also  capable  of 
once  more  germinating,  sometimes  after  the  lapse  of  sevc    ' 
years,  when  again  brought  under  favorable  conditions.    These 
conditions  are  (i)  a  suitable  temperature,  and  (2)  an  abundance 
of  moisture.    The  consideration  of  a  few  special  cases  will  per- 
mit of  a  clearer  conception  of  the  nature  and  operation  of  these 
conditions. 

That  all  fungi  are  not  equally  affected  by  the  same  degree  of 
heat  and  cold  is  one  of  the  elementary  facts  of  plant  physiology, 
while  it  is  also  equally  well  known  that  the  same  plant  will  be 
variously  affected  according  to  the  special  condition  of  growth 
in  which  it  is  brought  under  the  action  of  varying  temperatures. 
These  facts  arc  probably  illustrated  among  the  bacteria  in  a 


DECAY 


I8t 


more  prominent  way  thin  in  any  other  group  of  plants,  though 
the  general  relations  also  hold  true  for  all  the  higher  Jungi. 
Thus  among  the  bacteria  certain  forms  have  been  known  to 
survive  a  temperature  of  -  lo"  C.  or  even  -  ioo°  C.  when  the 
cold  is  applied  for  a  short  time  only.    On  the  other  hand,  Bacil- 
lus  thermophilus  thrives  vigorously  at  a  temperature  of  70°  C, 
while  the  spores  of  th(  cortmon  hay  bacillus  (B.  subtilis),  which 
are  destroyed  when  heated  in  their  nutrient  solutions  to  temper- 
atures exceeding  100°  C,  are  nevertheless  capable  of  resisting 
upwards  of  120°  C.  of  dry  heat.    From  these  and  similar  well- 
known  examples  it  may  be  concluded  that  the  specific  effect  of 
varying  temperatures  is  due  to  the  amount  of  water  present  in 
the  albuminoid  protoplasm,  —  a  conclusion  in  accord  with  the 
reduction  of  water  which  is  known  to  take  place  in  a  cell  when 
it  passes  from  the  active  vegetative  to  the  resting  state,  in  which 
form  it  manifests  its  highest  powers  of  resistance  to  extreme 
conditions  of  temperature.    This  principle  finds  its  further  illus- 
tration in  the  fact  that  the  vegetative  cells  of  fungi,  which  con- 
tarn  a  maximum  of  water  and  are  adjusted  to  certain  conditions 
of  temperature,  may  be  readily  killed  by  dryness,  for  which  pur- 
pose desiccation  at  the  ordinary  temperature  is  often  sufficient. 
Broadly  speaking,  the  bacteria  cannot  survive  a  temperature 
exceeding  50°  to  60°  C.  and  in  this  connection  a  statement  of 
the  thre*?  critical  points  in  temperature  for  a  few  well-known 
forms,  .       iven  by  Warming,  may  be  instructive: 


Hay  bacillus  (B.  subtilis) 

Anthrax  bacillus  (B.  anthracis) 

Cholera  bacillus  (Spirillum  cholerx-asiatlc.x) 
Tubercle  bacillus  (B.  tuberculosis) 


Turning  our  attention  to  the  fungi,  which  are  more  immedi- 
ately concerned  in  he  destruction  of  timber,  we  find  that  with 
the  exception  of  certain  specialized  forms  the  three  critical  points 
m  temperature  may  be  state    as  minimum,  i  °  to  2°  C. ;  optimum, 


I 


:S»' 


I 


l83 


ANAIOMY  OF   IHK  liVMNOsi'JlkMS 


20°  C. ;  maximum,  40°  C.  The  relation  of  moisture  and  hea; 
to  continued  life  conforms  to  the  same  principle  as  stated 
for  the  bacilli,  namely,  that  the  s|x)rcs  of  rcnicillium  glaucum 
and  Rhizopus  nigricans  rarely  gv  .ninate  if  exposed  for  one  or 
two  hours  to  ;.  r  which  has  been  heated  to  a  temperature  of  70° 
to  80"  C,  while  they  are  entirely  destroyed  at  82°  to  84°  C.  On 
the  other  hand,  spores  which  have  been  heated  in  their  own 
nutrient  fluids  to  a  temperature  of  54"  or  55°  C.  completely 
lose  all  power  of  germination  (84,  725). 

Although  but  little  is  as  yet  known  respecting  the  life  history 
of  the  fungi,  and  especially  the  particular  conditions  under  which 
the  germination  of  the  spores  occurs,  the  foregoing  facts  direct 
attention  to  the  great  divci  .ity  and  wide  range  of  the  conditions 
involved  for  different  species.  Fortunately  the  researches  of 
Hartig  have  made  it  possible  to  gain  an  insight  of  a  more  exact 
c?  ractcr  into  the  operations  of  one  of  the  most  destructive  fungi 
kn.  n,  the  dry  rot  (Merulius  lachrymans),  a  short  account  of 
which  may  serve  as  a  working  basis  for  all  fungi. 

The  spores  of  dry  rot  germinate  on  the  surface  of  damp 
timber,  and  the  growing  plant  quickly  jxinetrates  the  tissue; 
but  the  germination  of  the  spores  demands  certain  conditions 
which  are  fulfilled  by  the  presence  of  alkaline  products,  particu- 
larly those  which  are  ammoniacal.    It  will  therefore  be  found 
that  locations  where  there  is  bad  drainage,  especially  in  cellars 
and  stables  where  ammoniacal  products  are  likely  to  be  abun- 
dant, offer  exceptionally  favorable  situations  for  its  development. 
When  the  plant  has  once  entered  upon  its  course  of  growth  its 
extension  is  very  rapid,  and  it  thrives  wherever  the  air  is  con- 
fined, .varm,  and  damp,  though  it  is  well  known  that  air,  i.e. 
air  which  is  freely  circulating  and  which  contains  a  much  lov/er 
percentage  of  moisture,  will  cause  the  death  of  the  plant  in  one 
or  two  days,  except  f.i  -    >ply  seated  parts.    From  this  point 
of  view  it  may  be  obst.  ^ed  that  the  disease  is  readily  propa- 
gated in  badly  ventilated  cellars  or  in  confined  areas  where  air 
does  not  freely  circulate  and  there  is  a  tendency  to  the  coilec- 
fon  of  moisture.    Thus  in  the  construction  of  the  MacDonald 


DECAY 


1«3 


Ki.ginecrinK  Building  at  McGill  University  use  was  made  of 
very  hnc  timbers  of  I)o«gl;,s  fir  as  supf-orting  f)cams  to  carry 
the  heavy  fl.K,rs  of  the  upinrr  stories.  These  were  seated  in 
cast-iroii.  flanged  bed  |)lates.  Within  a  few  years,  in  the  room 
usetl  as  a  hydrauhc  laboratory,  the  timbers  had  developed  dry 
rot,  which  extended  upwards  from  the  base  for  a  distance  of 
about  one  foot.  The  obvious  cause  was  to  be  found  in  the  con- 
fined air  and  in  the  accumubtion  of  moisture  ondensed  from 
the  atmosphere  of  the  room.  In  another  ca'  brought  to  my 
notice  tlic  heavy  oak  roof  timbers  of  a  large  '  iding  developed 
an  e.xtensivc  growth  of  dry  rot.  Upon  examination  it  was  found 
that  the  air  of  the  low  attic  was  confined  and  no  circulation  was 
possible.  Openings  were  at  once  made  at  opposite  emls  and  a 
free  circaln.tion  establisi  -I.  The  difficulty  was  speedily  removed, 
and  there  has  been  no  incurrence  of  the  trouble  within  a  period 
of  about  fifteen  years. 

Our  k-owledge  of  the  way  in  which  and  the  condit\)ns  under 
which  dry  rot  oixirates  makes  it  jmssible  to  apply  effective  reme- 
dial measures  with  intellige.  :e.    These  measures  involve  : 

1.  Complete  ventilation. 

2.  Removal  of  all  sources  of  alkaline  and  particnlarly  of  ammoniacal 

products. 

3.  A  complete  removal  of  all  diseased  wood. 

4-  Treatment  with  .so  ne  fungicide,  such  as  -iric  sulphate,  he  .ondi- 
tions  are  such  as  to  make  other  remedies  in  any  way  ineffecti\ 

Finally,  the  observations  of  Dudley  (14.  44).  'liat  fungi  do 
not  penetrate  cedar  ties  unless  there  is  a  ^-.^d  supply  of  air, 
and  that  when  the  latter  is  cu'  . /f  the  pr  ..-h  stops,  once 
more  direct  attention  to  the  naf.  of  the  cttcctive  prevent- 
ive measures. 

From  these  considerations  it  becomes  obvious  that  for  fungi  in 
general  higher  temperatures  offer  correspondingly  more  favor- 
able conditions  for  growth,  which  is  also  accelerated  fy  an  in- 
crease of  moisture,  both  operating  within  certain  well-defined 
limits.  And  we  may  further  conclude  that  preventive  measures 
will  be  most  effective  under  those  conditions  which  involve  low 


1 84 


ANATOMY  OF  THE  GYMNOSPERMS 


temperature,  an  absence  of  moisture,  and,  if  possible,  a  complete 
exclusion  of  oxygen. 

3.   Their  mode  of  operation.    The  mycelium,  or  plant  body, 
of  the  fungus  consists  of  a  very  slender  thread  which  is  about 
7  M  or  less  in  diameter.    Comparing  this  with  the  normal  phys- 
ical openings  in  the  tissue  of  coniferous  woods,  it  is  found  to  be 
only  one  fourth  the  size  of  the  cavity  of  the  tracheid  (28  /i)  of 
the  spring  wood,  while  it  is  but  little  smaller  than  the  average 
tracheid  cavity  of  t!:e  inner  summer  wood  (10  ^),  and  twice  as 
large  as  the  cavities  of  the  tracheids  last  formed  (3.5  fi)  in  the 
wood  of  Juniperus  virginiana.    Within  this  same  species  it  is 
but  little  smaller  than  the  tangential  diameter  of  the  ray  cell 
(8.7  /i,),  while  it  is  about  twice  as  large  as  the  average  pore  of 
the  bordered  pit  (3.5  /*).    Red  cedar  was  selected  for  compari- 
son for  thf  reason  that  the  structural  features  referred  to  are 
relatively  small  and  they  represent  what  is  common  to  a  number 
of  species,  such  as  those  of  Torreya  and  Taxus.    But  it  must  be 
remembered  that  in  the  majority  of  coniferous  woods  the  open- 
ings referred  to  are  far  larger,  and  they  would  therefore  offcT 
correspondingly  more  favorable  conditions  for  free  development 
of  the  mycelijm.    From  these  facts  it  is  not  difficult  to  perceive 
that  when  spores  germinate  on  the  surface  of  a  timber,  on  a 
wounded  surface,  or  in  a  crack,  the  growing  plant  at  once  finds 
ready  access  to  the  interior  parts  through  the  natural  channels 
afforded  by  relatively  large  openings  in  the  tissue.  Such  entrance 
will  be  greatly  facilitated  in  proportion  as  the  surface  is  rougher 
or  the  tissue  is  in  any  way  lacerated,  since  such  laceration  not 
only  increases  the  size  and  number  of  the  initial  openings  but 
is  also  a  factor  which  contributes  to  more  speedy  disorganization 
of  the  organic  substance  of  the  cell  wall.  From  this  it  is  evident 
that  the  stumps  of  branches  which  have  been  left  in  a  ragged 
condition  either  through  wind  pruning  or  through  the  careless 
operations  of  the  forester  must  afford  conditions  highly  favor- 
able to  the  operation  of  decay.    Or  yet  again,  when  felled  timber 


cracks 

offer  inviting  places  for  the 


the  process  of  drying  before  it  is  rafted,  the  cracks 
lodgment  of  fungus  spores,  especially 


Decay 


'85 


those  of  the  rdypori,  which  abound  in  the  forests.    The  sub- 
sequent immersion  of  the  logs  as  they  are  floated  to  the  mill 
causes  the  cracks  to  close  and  favors  the  development  of  the 
spores  in  the  interior  of  the  log.    The  relatively  small  amount 
of  fungus  developed  under  such  circumstances  lies  dormant  and 
is  widely  distributed  wherever  the  prepared  lumber  is  used  for 
constructive  purposes.    If  such  boards  should  be  employed  in 
damp  and  close  situations,  such  as  a  cellar  or  poorly  ventilated 
basement,  the  fungus  will  find  most  congenial  conditions  for 
renewed  and  vigorous  growth,  and  all  the  characteristic  phe- 
nomena of  dry  rot  will  be  manifested.    An  instance  of  this  kind 
came  under  my  observation  some  two  years  since  in  a  city  house, 
where  the  wainscoting  of  the  basement  dining  room  was  once 
removed  ;  but  as  the  fungus  again  appeared  within  a  short  time 
and  attacked  the  entire  sheathing,  the  tenants  sought  safety  in 
removal  to  another  and  better  constructed  house.    A  second 
case  of  the  same  sort  was  brought  to  a  conclusion  during  the 
past  summer.    As  a  precautionary  measure,  about  a  year  ago 
the  infected  woodwork  was  all  removed  and  the  surrounding 
walls  were  cleaned  as  thoroughly  as  possible,  the  surfaces  being 
washed  with  a  solution  of  cupric  sulphate.    Eventually,  it  being 
found  impossible  to  check  the  trouble  without  much  more  exten- 
sive repairs  than  the  landlord  was  willing  to  make,  the  tenant 
brought  suit  and  secured  damages. 

When  the  fungus  has  once  been  established  through  any  of 
the  means  described,  and  the  conditions  continue  favorable,  it 
extends  with  great  rapidity  in  all  directions  from  the  original 
center,  being  guided  in  the  course  it  takes  by  conditions  of  nutri- 
tion rather  than  the  path  of  least  resistance,  carrying  with  it  all 
the  characteristic  features  of  disease  and  decomposition.  Wher- 
ever there  is  room  for  expansion,  as  in  seasoning  cracks  or  in 
the  cavities  arising  through  its  own  operations,  the  mycelium 
increases  greatly  and  gives  rise  to  massive  developments  of 
various  forms.  Thus  in  the  white  rot  of  the  red  cedar,  caused  by 
I'olyporus  juniperinus,  von  Schrenk  has  shown  that  the  cavities 
arising  through  the  action  of  the  fungus  are  lined  with  a  felt 


1 86 


ANATOMY  OF  THE  GYMNOSPERMS 


of  soft  brown  mycelium,  which  often  assumes  very  fantastic 
shapes  (69,  lo). 

In  the  diffusion  of  a  fungus  through  woody  tissue  two  impor- 
tant features  may  be  noted:    (i)  the  extent  and  direction  of 
development  are  determined  in  the  first  instance  by  the  distribu- 
tion of  food  materials  ;  (2)  the  distribution  and  progress  of  the 
mycelium  are  independent  of  the  presence  of  physical  openings 
in  the  structure.    A  few  specific  illustrations  may  serve  to  malce 
these  statements  clear.    No  matter  what  particular  channels 
may  have  permitted  the  mycelium  to  gain  access  to  the  interior, 
its  development  appears  to  arise  chiefly  and  first  of  all  in  the 
medullary  rays.    The  mycelium  extends  in  the  general  direction 
of  the  ray  structure  and  therefore  at  right  angles  to  the  principal 
lines  of  structure  for  the  wood  as  a  whole,  filling  the  individual 
cells  with  loosely  felted  masses  of  brown  hyphae,  from  which  are 
developed  short  and  variously  divided  branches.    These  latter 
are  particularly  connected  with  the  absorption  of  food  substances, 
and  they  are  appropriately  known  as  haiistoria.    It  very  fre- 
quently happens  that  such  growths  of  mycelium  may  be  nearly 
or  altogether  confined  to  the  structure  of  the  r.iy,  the  adjacent 
tracheids  being  wholly  devoid  of  them  ;  or  there  may  be  local 
areas  within  which  the  mycelia  extend  vertically  upward  and 
downward  from  the   ray,  invading  the   neighboring  tracheids, 
through   which    they  extend  for   long  distances.    These  facts 
suggest  that  the  medullary  ray  may  ofifer  more  favorable  condi- 
tions for  development  than  other  parts  of  the  structure,  and 
they  make  it  desirable  to  '     .nine  its  structural  features  some- 
what more  closely  from  this  point  of  view. 

An  examination  of  a  medullary  ray  as  exposed  in  radial  sec- 
tion shows  that  the  upper,  lower,  and  side  walls  —  particularly 
the  latter  — are  provided  with  definite  pits,  through  which  it 
would  be  possible  for  the  fungus  to  jiass  into  adjacent  cells  with 
very  little  opposition.  But  such  favorable  condition^  are  obvi- 
ously not  taken  advantage  of  to  any  great  extent,  since  neigh- 
boring tracheids  often  remain  quite  free  from  the  mycelium 
while  the  ray  cells  are  crowded  with  it.    This  would  seem  to 


DECAY  ,87 

imply  that  there  is  some  special  property  in  the  ray  itself  which 
favors  a  more  vigorous  growth  there,  and  serves  to  retain  the 
fungus  in  that  particular  locality.  The  terminal  walls,  as  in 
Abies,  I^rix,  Picea,  etc.,  are  perforated  with  numerous  pits,  which 
would  offer  a  somewhat  easy  path  for  the  radial  extension  of  the 
fungus.  But  such  openings  fail  to  satisfy  the  conditions  and 
explain  the  great  abundance  of  mycelium  found  in  the  rays, 
since  the  terminJ  walls  of  the  Cupressineae  are  not  pitted  but 
present  a  blank  wall  to  the  further  progress  of  the  fungus. 
Furthermore  it  may  be  shown,  as  will  appear  very  shortly,  that 
physical  openin^o  offer  no  determining  influence  upon  the  direc- 
tion of  growth  of  the  mycelium,  which  continues  in  the  originally 
selected  course  without  respect  to  the  structural  characteristics 
of  that  which  may  lie  in  its  path.  From  these  facts,  then,  it 
would  seem  that  the  structure  of  the  ray  does  not  afford  an 
adequate  explanation  of  the  observed  phenomena. 

The  medullary  ray  constitutes  perhaps  the  most  important 
structural  region  within  the  vascular  cylinder  with  respect  to 
the  accumulation  of  reserve  food.  This  is  deposited  in  the  form 
of  starch  and  other  easily  assimilated  products,  and  it  is  their 
presence  in  relative  excess  which  undoubtedly  determines  the 
abundant  development  and  localization  of  the  mycelia  within 
such  regions  in  the  first  instance.  If  this  hypothesis  be  regarded 
as  a  correct  one,  then  it  is  possible  to  see  how  the  -nycelia  gain 
access  to  other  structures  exactly  in  accordance  with  its  require- 
ments and  the  possibilities  of  finding  fresh  stores  of  food  mate- 
rial, which  may  be  held  to  appear  in  diminishing  quantities  as 
successive  areas  are  entered,  until,  the  more  available  forms  of 
food  having  been  exhausted,  the  cellulose  fabric  itself  is  attacked, 
and  with  its  disintegration  the  characteristic  features  in  the 
operation  of  the  fungus  are  expressed  in  recognizable  form.  In 
confirmation  of  the  view  thus  expressed,  it  will  be  found  to  be 
very  generally  true  that  next  to  the  medullary  ray  the  greatest 
development  of  the  mycelium  takes  place  in  the  tracheids  and 
resin  passages,  which  tiiey  traverse  in  a  longitudinal  direction 
(plate  9).    In  this  case  it  is  possible  that  the  opportunities  for 


1 88 


ANATOMY  OF  THE  GYMNOSPERMS 


free  growth  afforded  by  the  long  cavity  of  the  tracheid  or  resin 
passage  may  serve  somewhat  to  influence  the  direction  of  growth 
as  the  fungus  searches  for  food,  although,  as  in  the  previous 
case,  it  cannot  be  regarded  as  a  determining  factor  of  primary 
importance,  inasmuch  as  there  is  a  constant  tendency  to  the 
formation  of  branches  which  traverse  the  wood  at  right  angles 
to  the  walls.  The  third  phase  in  distribution  is  established  when 
the  vertical  strands  give  rise  to  hyphae,  which  are  developed  at 
right  angles  to  the  original  course,  and  which  then  traverse 
the  tissue  at  right  angles  to  the  principal 
lines  of  structure  (plate  lo). 

It  might  be  supposed  that  the  courst 
of  the  fungus  would  be  determined  by 
the  presence  of  physical  openings  in  the 
walls  of  the  tracheids,  and  that  the  myce- 
lium would  therefore  follow  an  irregular 
course  leading  it  through  the  various  bor- 
dered pits,  which,  as  previously  shown, 
offer  ample  opportunities  for  such  pas- 
sage.   Such,  however,  is  in  no  sense  the 
case.   In  fig.  48  a  radial  section  of  the  red 
pine  (Pinus  resinosa)  shows  very  clearly 
that  the  growth  of  the  fungus  is  wholly 
independent  of  physical  openings  of  any 
kind,  otherwise  it  would  take  advantage  of 
those  which  lie  in  its  immediate  neighborhood.  On  the  contrar>', 
its  course  does  not  deviate  from  the  original  direction  established 
at  the  point  of  emergence  from  the  main  filament.    Whenever 
in  Its  progress  the  mycelium  comes  in  contact  with  the  cell 
wall,  its  enzyme  attacks  the  latter,  and  by  solution  establishes 
an  opening  through  which  the  fungus  passes.    It  will  be  noted, 
nevertheless,  that  the  resistance  offered  by  the  wall  is  sufficient 
to  bring  about  a  great  reduction  of  the  mycelium,  which  is  always 
much  less  than  the  normal  diameter  within  the  limits  of  the 
wall.    In  thin-walled  cells,  where  little  resistance  is  offered,  the 
opening  thus  established  is  commonly  larger  than  the  mycelium, 


Fio.  48.  Pinus  Kr  jinosa. 
Hadial  section  showing 
the  progress  of  a  fungus 
mycelium  across  the  line 
of  s>-ucture,  and  its  pene- 
tration of  the  cell  wall, 
independently  of  the 
presence  of  pits,    x  350 


r^^ 


DECAY  ,89 

which  then  has  a  perfectly  free  passage;  but  in  all  highly 
lignified  tissues,  and  more  particularly  those  in  which  secondary 
growth  of  the  wall  is  excessive,  such  contraction  is  always  exhib- 
ited. This  action  of  the  mycelium  in  perforating  the  cellulose 
wall  is  by  no  means  exceptional  or  peculiar  to  the  fungi,  since  it 
appears  in  a  variety  of  forms  th^-ughout  the  plant  world  and 
constitutes  a  well-known  process  in  the  liberation  of  spores  from 
the  mother  cell,  as  well  as  in  the  progress  of  the  pollen  tube 
through  the  structure  of  the  style. 

It  now  remains  to   inquire  somewhat  more  particularly  into 
the  specific  action  of  fungi  as  expressed  in 

4.   Their  effects  upon  the  structure  and  their  relation  to  forms 
of  preservation  in  fossil  plants.    While  the  general  course  of  the 
physical  changes  in  decaying  wood  is  fair]     well  known,  ':here 
are  many  features  which  demand  more  thorough  and  extended 
study.    This  is  particularly  true  of  the  change."  which  arise  in 
the  ctUulose  an^  eventually  resolve  it  into  its  proximate  ele- 
ments, whereby  the  chemistry  of  decay  is  recognized  as  one  of 
the  mo!.t  obscure  problems  with  which  the  plant  physiologist 
has  to  deal    Nevertheless  reference  to  the  well-known  reactions 
for  cellulose,  as  already  given  (p.  49),  enables  us  to  form  some  con- 
ception of  the  nature  of  these  changes,  since  those  which  pro- 
ceed from  the  action  of  fungi  are  in  many  respects  parallel  with 
those  obtained  through  the  action  of  reagents.    The  alterations 
accomplished  by  the  latter,  either  through  the  action  of  an  acid 
or  of  an  oxidizing  body,  are  brought  about  in  the  fungi  by  the 
action  of  special  ferment  secretions  included  under  the  general 
name  of  enzymes.    But  here  it  is  to  be  noted  that  each  funj,us 
behaves  in  a  way  peculiar  to  itself,  and  gives  rise  to  specific 
effects  which  cannot   be  associated  with  other  fungi.    These 
differences  may  be  reduced  in  the  first  instance  to  two  groups, 
in  the  first  of  which  the  action  is  primarily  upon  the  intercellu- 
lar substance,  whereby  the  latter  is  destroyed  with  a  separation 
of  the  secondary  walls  from  one  another ;  in  the  second  place 
the  action  is  upon  the  secondary  Walls,  which  are  largely  removed 
with  the  production  of  a  skeleton  composed  of  the  primary 


igo 


ANATOMY  OF  THE  GYMNOSPERMS 


walls.  The  specific  action  in  such  cases  is  prubably  one  of 
hydrolysis,  whereby  the  cellulose  is  resolved  into  soluble  prod- 
ucts of  the  general  nature  of  glucose,  and  the  results  are  pre- 
cisely parallel  with  those  produced  by  Mangin's  maceration  or 
by  strong  sulphuri:  acid.  But  such  changes  shouH  ^.  studed 
through  the  recort^s  of  special  cases.  Tubeuf  (72,  38-39)  has 
shown  that  Trameies  pini  acts  in  the  first  instance  upon  the 
more  highly  lignified  portions  of  the  wall.  The  first  effects  of  its 
operations,  therefore,  are  expressed  in  the  solution  and  removal 
of  the  primary  wall,  while  the  secondary  and  tertiary  walls 
remain  behind  as  a  skeleton,  which  may  eventually  become 
corroded  and  disappei<r  after  prolonged  action. 

Precisely  the  same  action  has  been  reported  more  recently  by 
von  Schrenk  as  developed  in  the  white  rot  of  the  red  cedar 
through   the  action  of   Polyporus  juniperinus,  von   Schr.  (69, 
9-10).    The  holes  produced  in  the  trunk  of  the  tree  through 
the  action  of  this  fungus  often  contain  as  much  as  three  hun- 
dred grams  of  the  cellulose  fiber.    On  the  other  hand,  the  same 
author  shows  that  in  the  red  or  brown  rot  of  the  same  tree 
numerous  pockets  are  formed  in  the  wood.    These  are  occupied 
by  metamorphosed  wood  tissue  which  has  cracked  by  shrinkage 
so  as  to  form  small  cubes  adhering  to  the  walls  of  the  pockets. 
An  examination  of  such  brown  material  shows  it  to  be  the  resi- 
due of  the  original  structure  after  elimination  of  the  cellulose, 
the  action  involving  a  reduction  of  the  cell  wall  by  solution  of 
the  less  lignified  parts,  thus   reducing  the  original  structure 
to  the  primary  cell  wall.    Here  again  the  action  is  seen  to  be 
exactly  contrary  to  that  of  the  previous  case,  since,  while  in  the 
white  rot  the  soluble  substan.e,  or  hadromal  of  Czapek,  is  all 
removed,  le..ving  the  cellulose  behind,  in  the  brown  rot  the  cel- 
lulose is  removed,  leaving  behind  a  residue  which  von  Schrenk 
has  been  able  to  identify  with  the  so-called  hadromal. 

By  the  same  authority  identical  changes  have  also  been  shown 
to  arise  from  the  action  of  Polyporus  versicolor  in  producing 
the  soft  rot  of  Catalpa  speciosa  (68,  50-52).  Tubeuf  has  also 
directed  attention  to  the  fact  that  the  same  general  changes  may 


DECAY 


191 


arise  in  other  conifers  through  the  action  of  Polyporus  vaporarius, 
P.  Schweinitzii.  and  P.  sulphureus,  one  of  their  characteristic 
results  being  expressed  in  a  breaking  up  of  the  cell  wall  into 
a  series  of  spiral  fibers  corresponding  to  the  original  striation. 
This  feature  of  decay  is  \ery  commonly  expressed  in  macerated 
woods  among  existing  species,  and  it  is  exemplified  in  a  verv 
striking  manner  by  Pseudotsuga  miocena  from  the  Miocene  uf 
Oregon  (plate  11). 

Whatever  particubr  form  the  decay  effected  by  fung"  may 
take,  it  is  no  doubt  correct  to  say  t!iat  the  disorganization  of 
the  cellulose  is  due  in  general  terms,  and  in  '.he  first  instance 
at  least,  to  a  process  of  h.  drolysis.  Fron:  th.s  point  of  view  it 
is  possible  to  satisfactorily  explain  the  varying  degrees  of  resist- 
ance offered  by  tissues  of  different  degrees  of  modification, 
since  it  will  be  observed  that  the  decay  acts  inversely  as  the 
amount  of  carbon  present,  wherefore  the  unmodified  walls  are 
the  first  to  be  acted  upon,  the  cork  a.id  cutin  the  last. 

The  changes  thus  noted  as  arising  through  the  action  of  fungi 
have  a  more  or  less  profound  effect  upon  the  degree  of  perfec- 
tion with  which  structural  details  are  retained  w' en  the  plant 
eventually  becomes  silicifird  or  calcified  and  is  converted  into 
the  condition  of  a  fossil,  li  has  been  shown  that  even  when 
present  in  the  tissue,  the  destructive  effects  of  the  fungus  may 
be  inhibited  by  the  exclusion  of  oxygen,  with  the  result  that 
the  structure  is  preserved  in  a  most  perfect  manner  through 
indefinite  periods  of  time,  and  without  the  subsequent  infiltra- 
tion oi  mineral  matter.  Most  commonly  the  wood  exhibits  the 
effects  of  more  or  less  extended  decay,  which,  in  the  majority  of 
cases,  shows  a  removal  of  the  secondary  wall  and  the  formation 
of  a  thin-walled  skeleton,  which  readily  collapses  and  thus  gives 
rise  to  extended  distortion  of  the  whole  structure,  whereby  it 
becomes  exceedingly  difficult  to  recognize  even  the  genus.  If 
these  changes  proceed  simultaneously  with  the  infiltration  of 
mineral  matter,  the  latter  may  eventually  replace  the  former  to 
such  an  extent  that  while  the  lines  of  structure  are  presen'ed, 
they  are  but  faintly  defined  by  thin  lines  of  finely  granulated 


li 


193 


ANATOMY  OF  THE  GYMNOSPERMS 


matter  representing  the  carbon  residue  of  the  original  structure 
Such  a  condition  is  presented  in  various  species  of  f^  press 
oxylon  and  Pityoxylon  from  the  Permian  and  Cretaceous  of 
Kansas  (is,  76-77).  Eventually,  as  so  commonly  expressed  ii 
specimens  from  the  petrified  forests  of  Arizona,  the  sUica  may 
entirely  replace  the  organic  matter  with  an  absolute  obliteration 
of  all  structural  details.  Such  alterations  are  necessarily  regional 
and  local,  as  determined  by  the  more  or  less  energetic  action  of 
the  fungus  and  the  progress  of  infiltration,  of  which  two  factors 
It  IS  the  necessary  resultant. 

A  peculiar  combination  of  decay  and  infiltration  may,  under 
other  circumstances,  give  rise  to  a  false  structure  which  bears 
no  relation  whatever  to  the  normal.    This  has  been  recognized 
by  Penhallo-  on  former  occasions  (57,  1 17,  and  58.  25)  in  the  case 
of  the  so<alled  Celluloxylon  primaevum  of  Dawson,  which  he 
has  shown  to  be  nothing  more  tha-     eculiarly  altered  forms  of 
Nematophycus  Logani  and  N.  crassu..    No  similar  instance  ha 
yet  been  recorded  for  the  vascular  plants,  and  it  would  almost 
seem  as  if  the  alterations  noted  were  to  be  specially  identified 
with  the  more  resistant  forms  of  marine  algs.    The  peculiar 
changes  observed  in  these  plants  were  of  such  a  nature  as  to 
give  rise  to  tissuelike  figures,  which,  under  a  low  power,  present 
the  precise  aspects  of  a  coarse  parenchyma  tissue  in  process 
of  decay.    Such  appearances  led  the  late  Sir  William  Dawson 
to  recognize  in  Celluloxylon  primaevum  a  distinct  type  of  plant 
though  It  was  subsequently  shown  that  the  appearances  were 
wholly  due  to  highly  altered  forms  of  Nematophycus.    The  effect 
arises  from  the  fact  that  the  carbon  residue,  the  decay  of  which 
has  already  been  carried  to  an  extreme  point,  is  in  a  finely  gran- 
ulated  form,  which  admits  of  very  ready  redistribution.    The 
crystallization  of  the  infiltrated  silica  at  such  a  time  supplies 
exactly  the  necessary  conditions  for  such  redistribution.    Under 
these  circumstances  the  carbon  particles  arrange  themselves 
upon  the  surfaces  of  the  crystals  without  any  reference  to  the 
original  lines  of  structure,  but  in  such  a  way  as  to  produce 
definite  figures  of  the  size  of  the  silicious  crystals. 


NORTH  AMERICAN  GYMNOSPERMS 
Part  II  —  Systematic 


■lai 


NOTE 

Genera  and  species  which  are  also  represented  in  the  fossil  sute  are 

indicated  by  *. 
Genera  and  species  which  are  exclusively  found  in  the  fossil  state  are 

indicated  by  ••. 


Part  II— Systematic 


SYNOPSIS  OF  GENERA   FOR  THE  CORDAITALES. 
GINGKOALES,  AND  CONIFERALES 

A.   Retin  pauagei  and  fuiiform  rays  present. 
I.  Fusiform  rays  narrow,  the  terminals  .  hiefly  long  and  abruptly  linear; 
the  cell.  «,her  small  and  thick  called.    Res.n  pa««ges  with  thkl 
walled  epithelium  and  chiefly  without  thylo.es. 
Tracheids  (radial)  with  spirals,  at  least  in  the  spring  woe  1 

Resm  celU  scattering  on  the  outer  face  of  the  summer  wood. 

Tracheids  wholly  without  spirals.  '*'  ^•*'"»°«»"K»  <P-  »7i). 

I'its  on  the  tangential  walls  of  the  summer  tracheids 

Resin  cell,  present  but  scattering  on  the  outer  face  of  the  summer  wood 
Resin  cells  wholly  wanting.     '^    '-»"*<?■  ^76). 
,,    „    .,  20.  Picea  (p.  281). 

n.  Fustform  rays  (tangential)  chiefly  broad,  the  cells  large,  the  resin 
{hTsM*  *"''  """•**"«'*?"'«"""' *"d  strongly  developed 

Tracheids  wholly  without  spirals. 
Resin  cells  wholly  wanting. 

Pit.  on  the  tangential  walls  of  the  summer  tracheids. 
Ray  tracheids  not  dentate. 

21.  Pinus  (Section  I,  p.  305). 
P«U  on  the  tangential  walls  of  the  summer  tracheids  usually  wanting 
Ray  tracheids  dentate. 
,Ti    V    ;  .  2'-  Pinus  (Section  11,  p.  J 18). 

HI.  Fusiform  rays  (tangential)  wholly  wanting.    Resin  pas.sages  (trans- 
verse)  when  present  usually  incompact  rows  on  the  outer  face  of 
the  s  immer  wood  of  dUtant  growth  rings,  imperfectly  formed. 
Resin  cells  pro.,  inent. 

int,s  on  the  lateral  walk  of  the  ray  cells  usually  with  a  conspicuous  border. 

the  orifice  very  large,  oblong,  the  pits  very  prominent, 
p.,  .      ,  '3-  Sequoia  sempervirens  (p.  224). 

orificV   T  r",^  °'  ""=  '^^  ""^  "^^  ^"''"'-  *'"»  ^  '>»^<"^>y  "blong 

orifice.    Terminal  walls  of  the  ray  cells  strongly  pitted. 

p„.;„     11  '7.  Tsuga  Mertensiana  (p.  270). 

r:t,i;::rg'"°"°''^*'°'^^""°"*'^^ 

•9S 


196 


ANATOMY  OF  THE  GYMN06PERMS 


n 


ii 


PlU  on  th«  kitral  walU  o(  iht  ray  c«ll>  imall,  «impU.  ttliptlcal. 
Tarminal  walla  of  iht  ray  ctib  mora  or  !•••  iirongly  i?Uiad. 
16.  AbU*  (p.  J5J). 

B.  RaPin  paaaagas  and  funlform  ray*  wholly  wantinf. 
I.  TraehtUJa  (radial  or  iangtntlal)  b«  ring  thin  tpiral  bands  in  1-4  aariaa. 
Ray  calla  (tangantlal)  narrowly  oblong. 

Trachaid.  (tranavarta)  chiafly  thick-walled  and  variable,  the  lumans  usuall* 
conapicuoualy  rounded,  the  structure  somewhat  compact  (except  T.  flori 
dana),  the  spirala  rather  close.  ' 

Kay  cella  (tangential)  broad,  oval,  or  oblong. 

Timchaidi  (transverse)  Urge,  chiafly  squarish,  and  rather  thin  walled,  the 
atnictura  rather  open  throughout,  the  spirals  rather  open. 

5.  Torreya  (p.  jio). 

II.  Tracheida  (radial  or  tangentUl)  wholly  devoid  of  spirals. 

I.  Wood  nonresinous,  commonly  bearing  idioblast*  with  sphere 

cryatala;  the  tracheida  of  j  kinds  (transversa). 

4-  Gingko  (p.  J09). 

a.  Wood  resinous,  devoid  of  crystal  bearing  idioblasts ;  the  tracheida 

(transverse)  all  of  1  kind. 

Resin  cella  (transverse)  prominent  and  in  more  or  less  conspicuous,  taneeiiiii.! 
bands,  sometimes  of  distant  growth  rings  or  again  widely  scattering 
Termmal  walls  of  the  ray  cells  entire,  straight,  more  rarely  curved. 

PlU  on  the  lateral  walls  of  .he  ray  cell,  large,  with  a  dUtinct  border 
Resin  cells  distinctly  zonate. 

Pi's  on  the  lateral  walls  of  the  ray  cells  round,  the  narrowly 
oblong  orifice  distinctly  diagonal,  the  border  very  prominent. 
10.  Taxodium  (p.  217), 
Reain  cells  scattering. 

Pita  on  the  lateral  walls  of  the  ray  cells  oval,  the  oblong  orlen 
ticular  onfice  usually  parallel  with  the  cell  axis,  the  border 
often  narrow,  sometimes  ob.scure. 

13.  Sequoia  (p.  223). 
Terminal  waib  of  the  ray  cells  sparingly  pitted. 

Pita  on  the  lateral  walls  of  the  ray  celU  wholly  simple  or  with  an  incn 
spicuous  border,  chiefly  small. 

Rays  (tangential)  broad,  very  sparingly  resinous,  often  2-seriate  at 
least  m  part. 

II.  Libocedrus  (p.  219). 
PiU  on  the  lateral  walls  of  the  ray  cells  distinctly  bordered 

Rays  (tangential)  usually  rather  narrow,  more  or  less  stronely  resin- 
ous, I  seriate.  "  ' 

15.  Juniperus  (p.  244). 

Terminal  walls  of  the  ray  cells  entire  or  locally  thickened,  usually  much  cu,  v  -d, 
sometimes  straight.  ' 


,  ^   'ftBfg'fflfflE'it* 


SYNOPSIS  OF  (;enera 


197 


"^moillnUn^""*'  """''  '"  '^'^'  '"""^  *"•''  *'•"•'*"«•  *«»•• 
Ray  cell*  (Ungtntial)  narrowly  obiong. 

li.  Thuya  (p.  220). 
Ray  cell.  (langantUl)  rathtr  broad.  ih«  c.ll.  round,  oval  or  Iran.- 
v«r»ely  oval,  rarely  oblong. 
Summer  wood  uiually  ihln  and  of  open  itructure 

Pit!  on  the  tangential  wall,  of  the  lummer  trachelda  uiually 
large  and  open,  prominent. 
Rayi  (tangential)  not  ttry  numeroua. 

14.  Cupretaua  (p.  iiX). 
Rayi  (tangential)  ter)>  numeroua. 

9-  Podocarpua  (p.  f6). 
Pi«a  on  the  tangential  walla  of  the  aummer  truheida  very 
nat  and  not  very  prominent. 

7.  Thujopsia  (p.  J15). 
SuiT'Mr  wood  dense,  the  .pring  wood  open,  thin  walled. 
_       ,     ,  8.  Cryptomeria  (p.  ji6). 

Terminal  wall,  of  the  ray  celU  thick,  more  or  leu  coaraely  pitted. 

Re»in  cell.  (tran.ven.e)  not  very  prominent,  remote,  and  more  or  le*. 

:X  rAblLr""  '""  °'  "•  •"""""  ''°°''  •°'"-"""  """"^ 
Ray.  (radial)   without  tracheid.  (rarely  present  in  A.  baUamea) 
•  6.  Abies  (p.  153). 
Resm  celU  (transverse)  rather  prominent,  more  or  le.-.  numerous  on  the 
outer  (ace  of  the  summer  wood,  rarely  lonate. 
Rays  (radial)  with  conspicuous  tracheid*. 
1.    •  '7'  '''•UR*  (p-  2>jS). 

KeMn  cells  (transverse)  entirely  wanting,  being  sometime,  replaced  by  resinous 

StX      "' ''''''  '""'"* "'°"« '•"  »«»"»">  «y«. "  --«'-. 

Bordered  pits  multiseriate,  hexagonal. 

Restn  when  present  contained  in  tracheid.  (transverse)  and  foriping  pUtes 
(radwl)  simulatmg  Sanio's  bands,  or  opposite  ray.  (tangen.     | 
Growth  rings  not  determinable. 

Tracheid8(transverse)  chiefly  equal  and  in  very  regular  radial  rows. 

I.  Cordaites  (p.  198). 
Tracheids  (transverse)  very  unequal  and  in  irreguUr,  radial  rows. 
3.  Ataucaria  (p.  203). 
Growth  rings  obvious,  but  poorly  defined. 

n    J       .    .     .  3'  L)<>mmara  (p.  201). 

Bordered  pits  in  i  'ow.  *^      ■*' 

Resin  wi^n  present  contained  m  tracheids  (transverse)  and  forming  plate* 
(radiai)  simulating  Sanio's  bands,  or  opposite  rays  (tangential). 
Growth  rings  not  very  well  developed. 
0    .       .  3    Araucaria  Bidwillii  (p.  20J). 

Kesm  when  present  massive  (radial),  not  in  plates. 
Growth  rings  very  prominent  and  well  defined. 
16.  Abies  (p.  T53). 


1    .  «!• 


198  ANATOMY  OF  THE  GYMNOSPERMS 


I.  CORDAITALES 

Growth  rings  rarely  well  defined.  Wood  more  or  less  resinous,  but  devoid 
of  specialized  resin  cells  or  resin  reservoirs.  Medullary  rays  all  of  one  kind 
Bordered  pits  on  the  radial  walls  of  the  tracheids,  hexagonal  and  multiseriate 


1.   *  •  COROAITES,  Unger.    Plates 


12  AND  13 


Transverse.  Pith  of  the  Sternbergia  type,  the  cells  large,  thin-walled,  often 
resinous.  Growth  rings,  when  present,  obscure,  rarely  somewhat  conspic- 
uous. Specialized  resin  cells  and  canals  wholly  wanting  except  in  the 
bark,  where  they  take  the  form  of  tubular,  branching  canals  without  epi- 
thelium, extending  in  the  general  direction  of  the  stem-axis.    Tracheid.s 

*.  JV^§^'  ''*^'!'  r"*"'  ™nsP'cuously  squarish,  and  often  resin  bearinir 

Kadial.  Elements  of  the  protoxylem  spiral  and  scalariform,  and  often  show- 
ing a  graduated  transition  into  tracheids  with  bordered  pits  Tracheid.s 
with  hexagonal,  bordered  pits  throughout,  on  their  radial  walls  only, 
m  i-s  rows.  Ray  cells  usually  of  one  kind  only;  the  upper  and  lower 
walls  thin  and  not  pitted ;  the  terminal  walls  thin,  not  pitted,  generally 
curved  ;  the  lateral  walls  with  bordered  pits  generally 

Tangential.  Medullary  rays  rather  numerous,  i-seriate  or  often  2-seriate  in 

port. 

This  genus  is  wholly  extinct  and  occurs  only  in  Paleozoic  strata.  For  a 
more  detailed  account  of  the  thirteen  known  North  American  species 
see  Penhallow,  North  American  Species  0/ Dadoxylon,  Trans.  R.  S  C  ' 
VI,  iv,  51-97,  1901. 

Synopsis  of  Species 

The  following  synopsis  is  given  provisionally  as  an  aid  to  identification  of 
the  various  species,  without  implying  the  absoli-te  value  of  the  differenti.il 
characters. 

I.   Crmvth  rings  present 

I.  C.  pennsylvanicum. 

II.    Growth  rings  obscure  or  obsolete 
A.  Ray  elements  of  two  kinds,  tracheids  and  parenchyma 
Bodered  pits  in  2-3,  rarely  4,  rows. 

Ray  cells  (tangential)  oval  or  oblong,  often  narrow. 

2.  C.  Clarkei. 

B.  Ray  elements  of  one  kind  only 
Bordered  pits  in  groups  of  6-13. 

Pits  on  the  lateral  waUs  of  the  ray  cells  3-6,  chiefly  4,  per  tracheid. 

3.  C.  Newberryi. 


CORDAITES 


199 


Bordered  pits  in  one  row,  compressed. 

Ray  cells  (tangential)  broad,  round,  or  squarish. 

4.  C.  recentium. 
Bordered  pits  in  1-3,  chiefly  2,  rows. 

Ray  cells  (tangential)  broadly  oval. 

Ray  cells  about  31-57  /i  broad. 

5.  C.  hamiltonense. 
Ray  cells  about  28-37  yn  broad. 

Pits  on  the  lateral  walls  of  the  ray  cells  about  1-4  per  tracheid. 

6.  C.  illinoisense. 
Ray  cells  (tangential)  oval  or  round. 

Pits  on  the  lateral  walls  of  the  ray  cells   1-8,  chiefly  2-3    per 
tracheid.  ' 

7.  C.  materioide. 
Ray  cells  not  determinable. 

8.  C.  annulatum. 
Bordered  pits  in  2-5  rows. 

Ray  cells  (tangential)  oval  or  oblong. 

Pits  on  the  lateral  walls  of  the  ray  cells  2-4,  chiefly  4,  per  tracheid. 

9.  C.  ouangondianuni. 

Pits  on  the  lateral  walls  of  the  ray  cells  4-10,  chiefly  6,  per  tracheid. 

10.  C.  acadianum. 
Ray  cells  (tangential)  broad  or  squarish. 

Pits  on  the  lateral  walls  of  the  ray  cells  2  per  tracheid. 

11.  C.  ohioense. 
Ray  cells  (tangential)  oval  or  round. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-5,  chiefly  1-2,  per 
tracheid. 

12.  C.  materiarium. 
Bordered  pits  in  5  rows. 

13.  C.  Hallii. 

1.  C.  pennsylvanicam,  Dn. 

Transx'erse.  Tracheids  44  x  44  ^  broad,  the  walls  6.7  ^  thick.  Growth  rines 
present,  the  summer  wood  about  8  tracheids  thick,  the  tracheids  about 
12.5  fi.  radially,  the  walls  3.1  y,  thick.  Resin  passages  and  resin  cells 
wsntinir. 

Radial.  Ray  cells  all  of  one  kind,  conspicuously  but  gradually  narrower 
toward  the  ends,  equal  to  about  3  tracheids ;  the  lateral  walls  with 
round  or  oval  pits,  about  2-3  per  tracheid. 

Tangential.  Rays  medium,  broad,  the  cells  round  or  transversely  oval,  vari- 
able,  25-31  abroad.  •'         ' 

The  Carboniferous  at  Pittsville,  Pennsylvania. 


200 


ANATOMY  OF  THE  GYMNOSPERMS 


2.  C.  Clarkei,  Dn. 

Transverse.  Growth  rings  obscure  or  entirely  wanting.  The  tracheids  about 
41  X  49  ^  broad,  their  walls  12.5/1  thick. 

Radial.  Bordered  pits  numerous  throughout  the  tracheids,  in  2-3,  more 
rarely  in  4,  rows.  The  elements  of  the  medullary  rays  of  two  kinds ;  the 
parenchyma  cells  thin-walled  and  devoid  of  pits,  about  equal  to  3 
tracheids ;  the  ray  tracheids  long,  interspersed,  and  bearing  on  their 
lateral  upper  and  lower  walls  numerous  crowded,  bordered  pits. 

Tangential.  Rays  very  variable,  commonly  i -seriate  but  sometimes  2-seriate 
in  part ;  the  tracheids  usually  distinguished  by  their  narrow  form  and 
pitted  walls. 

Hamilton  Group,  Ithaca,  New  York. 

3.  C.  Newbenyi,  (Dn.)  Knowlton 

Transverse.  Tracheids  about  44X  55  /*,  the  walls  about  12.5  ^  thick. 

Radial.  Ray  cells  resinous  and  starch  bearing,  long  and  narrow,  about  equal 
to  3-7  tracheids,  tl:-  ends  conspicuously  narrower;  the  pits  on  the 
lateral  walls  3-6,  chiit»y  4,  per  tracheid,  the  slitiike  orifice  nearly  the 
full  diameter  of  the  pit.  Bordered  pits  numerous,  round,  about  9.3/1 
broad,  distributed  in  radially  disposed  groups  of  about  6-13;  the  ori- 
fice diagonal,  neariy  the  diameter  of  the  pit. 

Tangential.  Rays  of  medium  height,  i-,  2-,  or  rarely  3-seriate  in  part ;  24-55 
/*  broad,  the  oval  or  round  cells  all  thin-walled. 

Hamilton  Group  (Middle  Devonian)  of  Ohio  (Newberry)  ;  Carboniferous  of 
Ohio  (Claypole). 

4.  C.  recentium,  Dn. 

Transverse.  Tracheids  47  x  53  /i  broad,  the  walls  much  reduced  by  decay 
Radial.  Ka.y  cells  all  of  one  kind,  about  equal  to  2  tracheids ;  the  lateral 
walls  with  round  pits  about  i  (?)  per  tracheid  ;  the  cells  conspicuously 
narrower  at  the  ends.  Bordered  pits  in  a  single  row,  compact,  large, 
compressed,  and  transversely  oval  or  oblong,  15.6  x  22  /a,  the  orifice 
very  variable  from  oblong  to  round,  often  eccentric,  but  typically  round 
and  central.  When  distant  the  pits  are  round  and  smaller. 
Tangential.  Rays  medium,  i-seriate  or  2-seriate,  the  very  broad  ceUs  41  u. 
thin-walled,  round,  and  squarish. 

The  Permian  or  Permocarboniferous  of  Prince  Edward  Island. 

5.  C.  hamiltonense,  Penh. 

Transverse.  Tracheids  very  variable,  growth  rings  obscure. 

Radial.  Structure  of  the  medullary  rays  not  determinable.    Bordered  pits 

hexagonal,  in  2  rows  throughout. 
Tangential   Rays  numerous  and  variable,  31-57  /i  broad;  the  cells  very 

variable  in  form  and  size,  thin-walled,  often  broader  than  high,  chieHy 

i-seriate,  often  more  or  less  2-seriate. 

Genesee  shales  (Hamilton  Group)  of  Ontario  County,  New  York. 


CORDAITES 
6.   C.  illinoisenae,  Dn. 


20 1 


'^"etiiJanT^^iT"'"  °'  '-^^  '"^"-  '^'  ^''"'y  oval, 

'"Ti^rf?,,*.''*""''"'  °'  ""■'  '^'»'""''  Ka"».  i  .he  Coal  M.„«,es  of 
Rock  Ijland,  Illinoi.,  and  Boonsboro,  Iowa  (I).  "'meajuresol 

7.  C.  nuterioide,  Dn. 

''""SjH„^"*Skto"„k,?:i-.>  '■™"''  "■=  ••«»  - ' "  «-i=i- 

*e  kniicula,  o,  oblong  S5  n.I?lv  ^Uf  ^tb.  J-  '"^'  >"'  i™'"'"  ■ 
Bordered  pte  hexaRonll,  In  "".X^'"   ^wf'  ''"™'"  ■"  *=  P"' 

"rn!'5fB™i"';;-::'r;,i',r-~'-^-"-- 

8.   C.  annulatum,  Dn. 

"~^oSrdZ''co*bl&dt=cr«?S"Ss'i^-r; 

yf  „/,'^  V,-"  '  '"'""';  ";=  ""'»  "'°*  "Itenuated  by  decay 
*""Srb™"rin1-tchiS;2;r1-"'-"'-    '-*"^  P"-  ^".«on„, 
'""■Sr,h  JStaKEi  ■"  »""■  "-^  "y  O-y  '»<■  P'e...re  ,„ 
Middle  Carboniferous,  Joggins,  Nova  Scotia 


9.  C.  ouangondianum,  Dn. 

^™rnon^e"''^''^  =''°"*  '' "^  ^' >-  •'^-'^'  ^"^^  -"«  9-3  M  thick.   Growth 
AW/a/.  Bordered  pits  numerous  tliroughout  the  tracheids  in  ->    .   rhi.a 

Middle  Devonian  of  New  Brunswick. 


,  'wM^ 


202 


ANATOMY  OF  THE  GYMNOSPERMS 


10.  C.  acadianum,  Un. 

Transverse.  The  large  tracheids  are  about  62  x62  ^  broad,  the  walls  9.5/1 

thick.    Scattering  tracheids  show  resinous  contents. 
Radial.  Ray  cells  often  somewhat  abruptly  contracted  at  the  ends,  equal  to 

2-4  tracheids;  the  lateral  walls  with  numerous  round  or  oval  pits,  4-10 

per  tracheid,  chiefly  about  6,  the  border  often  very  narrow,  the  oblong 

orifice  three  fourths  the  diameter  of  the  pit.    Bordered  pits  numerous, 

hexagonal,  12.5-16  /*  broad,  crowded  in  2-5  rows. 
Tangential.  Rays  very  variable,  ranging  upwards  of  60  cells  high,  resinous, 

more  or  less  2-seriate  throughout,  the  oval  or  oblong  cells    17-31  fi 

broad. 

Middle  Coal  Measures,  Joggins,  Nova  Scotia ;  Port  Hood,  Mira,  ai  J  Glace 
Bay,  Cape  Breton ;  Dorchester,  New  Brunswick ;  St.  George's  Bay, 
Newfoundland. 

11.   C.  ohioense,  Dn. 

'''ransverse.  Tracheids  47X  56  /x  broad,  the  walls  12.5  fi.  thick. 

Radial.  Ray  cells  chiefly  short,  about  equal  to  2  tracheids,  straight,  or 
somewhat  abruptly  contracted  at  the  ends ;  the  pits  on  the  lateral  walls 
oval,  with  a  promine.  t  border,  apparently  2  per  tracheid,  but  not 
exactly  determinable  on  account  of  extended  .lecay.  Bordered  pits  in 
3-4  rows,  sometimes  2  rows  throughout  the  tracheid,  hexagonal,  abi, . 
12.5  ijL  broad. 

Tangential.  Rays  numerous,  upwards  of  25  cells  high;  broad,  about  41  j.., 
conspicuou.'y  squarish,  i-  or  often  2-seriate  or  3-seriate  in  part. 

New  Lisbon,  Ohio. 

12.   C.  materiarium,  Dn. 

Transverse.  Tracheids  45  x  75  /i  broad,  the  walls  7.8  n  thick.  Scattering 
tracheids  show  resinous  matter. 

Radial.  Ray  cells  straight,  somewhat  narro  ved  at  the  ends,  eo-.al  to  about 
2-6  tracheids  ;  the  pits  on  the  lateral  wal  s  large,  oval,  round,  or  oblonj;, 
narrowly  or  even  obscurely  bordered.  1-5,  chiefly  1-2,  per  tracheid. 
Bordered  pits  numerous  throughout  the  tracheids,  chiefly  in  2,  some- 
times in  3-4,  rows,  hexagonal,  or,  when  more  distant,  oval,  about  12.5  fi 
broad. 

Tangential.  Rays  i-seriate  or  2-seriate  in  part,  upwards  of  40  cells  high,  the 
oval  or  round  cells  17-35  !>■  broad. 

Holmes  County,  Ohio  (Newberrj-)  ;  Upper  Coal  Measures  of  Malagash, 
Pictou,  Joggins,  Belen,  and  Cambon,  Nova  Scotia  ;  St.  George's  Bay,  New- 
foundland ;  Mirimichi,  New  Brunswick  ;  Glace  Bay,  Cape  Breton ;  Marion 
County,  Illinois. 

13.   C.  HaUi,  Dn. 

"  Wood  cells  very  large,  with  5  rows  of  contiguous,  alternate,  hexagon.i! 
areoles.  Medullary  rays  frequent,  and  with  as  many  as  30  rows  of  cells 
superimposed  "  (Dawson). 

Middle  Devonian  of  Ontario  County,  New  York. 


t. 


araucaria 

2.   •DAMMARA,'  Lami..     Platf.s  14  and  ij 


203 


1-  D.  austndls,  Steud. 
Kauri*.     CowdU  Pin* 

walled  passing  gradually  into  the  spring  wood.    Spring  wood  of  tt 

and  lower  wa "s  th.n  and  not  pitted  ;  the  ten^inal  wails  U>in 'and  en'^ke 
not  locally  thickened  ;  the  lateral  walls  with  round,  bordered  dUs  and  a 
fadfZ  ihickenei"  ''""'^'  '"^  ^'l  *^^^'^^"^-    Wo^tra'heid'    usually 

TSte  t"hf.:^   "^"  ::*^°'i^   ^''^''^^     The   LZutrays  strictly 

thirwS;^ot"too'r''  ""^'^"^''  °^^'  °'  '^^"— >  --'.  t£ 


•  ARAUCARIA,  Juss.     Plates  16  and  17 


Framverse.  Growth  rings   not  determinable, 

Resin  passages  and  specialized  resin  c 

bearing  tracheids  more  or  less  promii 
luuUal.  Rays  wholly  devoid  of  trache-'ds     1 

multiseriate.    Spiral  tracheids  wholly  wai. 
lan^^enttal.  Fusiform  rays  wholly  wanting. 

'  The  genus  Protodammara  ha.s  been  created  by  Hollick  and  Jeffrey  for  the 
reception  of  certain  cretaceous  cones,  but  at  present  it  does  not  contain  an/.^od 


■  at   most   poorly  defined, 
entirely  wanting.     Kesin- 

d  pits  usually  hexagonal, 


J04 


ANATOMY  OF  THE  (lYMNOSPERMS 


Synopsis  of  Species 

I.  ARAUCARIA 

Existing  species  confined  to  tlie  southern  hemisphere  and  unknown  in  the 
fossil  state. 

A.  Growth  rings  obscure  or  wanting 
Bordered  pits  in  1-3  rows,  hexagonal. 

Resin-bearing  tracheids  (radial)  wanting. 

1.  A.  Cunninghamii 
Resin-bearing  tracheids  (radial)  numerous,  the  resin  in  thick  plates  like 

Sanio's  bands. 

2.  A.  excelsa 

B.  Growth  rings  obvious 
Bordered  pits  crowded  in  i  row,  more  or  less  rounded,  not  strictly  hexagonal. 
Rays  (radial)  locally  and  strongly  resinous,  the  lateral  walls  at  such 
points  with  sieve-plate  structure. 

3.  A.  Bidwillii 

II.  •  •  ARAUCARIOXYLON 

Extinct  species  occurring  in  Mesozoic  and  Tertiary  strata,  the  remains 
bei.ig  usually  silicified  or  calcified. 

A.  Growth  rings  obscure  or  wanting 
Bordered  pits  in  r   3  rows. 

4.  ♦  •  A.  Woodworthi. 
Bordered  pits  in  1-2  rows. 

5.  *  •  A.  virginianum. 
Bordered  pits  chiefly  in  i  row. 

Growth  rings  wholly  wanting. 

6.  •  *  A.  Prosseri. 
Growth  rings  present  but  obscure. 

7.  *  •  A.  arizonicum. 
B.  Growth  rings  obvious 

Bordered  pits  in  1-2  rows. 

8.  •  *  A.  Hoppertonse. 
Bordered  pits  chiefly  in  I  row. 

9.  •  •  A.  Edvardianum. 
Araucarioxylon  cbscurum  of   Knowlton  {Mesozou    Floras  of  the    United 

States,  p.  418)  does  not  belong  here  at  all,  but  is  cited  now  for  future 
reference. 


ARAUCARIA 


ao5 


1.   A.  CnimiiigluunU,  Sweet. 
Af^^eion  Bay  Pin,.    Hoof  Pin,.     Colonial  Pin,.     Cooron,.    Cun,H.r,u.     Coonan. 
Transvene.  Growth  rings  not  clearly  discemihi.-  ■  ,r,^k.ij 

T:i:Z^'i^^^lt^^^''^^^-    Pi-  on  theXntial-wXo] 

'''''Cpart-''the'ceirr'''.'''"  *"  '"*'''""'■  '•"'"''"•''=  ''"'•retimes   ^-seriate 
wX  thin  "^  ^^'^^-  ""•='!"'"'  ''^=»'  «^  transversely  ova?;  the 

2.  A.  excelsa,  R.  Br. 

A'orfolk  Jslaud  Pin, 
Transvfrse.  Growth   rings   not   detprminnW^ .    .i,„  •  . 

3.   A,  BidwilUi,  Hook. 
Bunya-Bunya 

'^'"Sure^inTh^'j'T  '""""'^  ^"'  ^^^^'^  ''^"""^'^  ^y  a  .slightly  more  open 
out    IkI  f '''■'y  fP""S  wood  :  the  structure  rather  dense  throuX 

Ssnotv.r        ^-'^''^'f"  ^hick-walled,  round-hexagonal  MeduS 
roiroTtrrKr'"'"''  '°*^^'>'  ^^--^  ^"'"°"-^'  •  «»  ''de,  distant" ^ 

"'''IL'^nrcet'^tTonV;^^^^  ^""''  ^^"'^'  ?  "^^^^'^'^^  "^  ^  tracheids ; 

the  unn^r  in^i     ^^  resinous ;  conspicuous!)  contracted  at  the  ends  • 

™ir"  ■^L^lnuS'.'SSr.^Sr'- 
gn,  marginal  cells  forming  high,  vertical  series.    WhJre   resin  i; 


J; 


a 


■«   \\ 


2o6 


ANATOMY  OF  THE  GYMNOSPERMS 


deposited  the  lateral  walls  of  groups  of  cells  bear  numerous  rounded 
pits,  giving  a  sieve-plate  structure.  Bordered  pits  crowded  in  i  row, 
more  or  less  rounded,  not  hexagonal,  as  broad  as  the  narrow  tracheids. 
Pits  on  the  tangential  walls  of  the  summer  wood  wanting. 
Tangential.  Rays  low,  only  a  few  cells  high,  numerous,  resinous ;  the  cells 
oval,  broad,  thin-walled,  strictly  i-seriate. 

4.  •  •  A.  Woodwotthi,  Kn. 

"  Transverse.  Annual  ring  very  obscure  and  not  visible  to  the  naked  eye,  but 
on  examination  under  the  microscope  it  is  found  to  be  present  and  to 
consist  of  only  2  or  3  slightly  smaller  and  thicker-walled  cells.  The 
wood  cells  are  only  moderately  thick-walled  and  are  quite  uniform 
in  size. 

"  Radial.  This  .section  shows  to  the  best  advantage  the  character  of  the  wwmI. 
Tlie  wood  cells  are  shown  to  be  long,  sharp  pointed,  and  to  be  provided 
with  usually  2  rows  of  bordered  pits,  although  cells  are  common  on 
which  there  is  but  a  single  .series.  Cells  on  which  there  are  3  rows  of 
pits  are  much  rarer.  When  in  a  single  row  the  pits  are  contiguous  and 
but  slightly  modified  in  shape  by  pressure.  When  the  pits  are  in  2  rows 
they  usually  occupy  the  center  of  the  cell  and  are  contiguous  and 
slightly  hexagonal ;  but  occasionally  the  2  rows  may  be  slightly  se|> 
arated  and  then  may  have  the  characters  of  the  single  rows.  When 
there  are  3  rows  of  pits  they  are  close  together  and  markedly  hexagonal. 
The  average  diameter  of  the  pits  is  about  0.015  "!•"■.  and  that  of  the 
inner  pore  about  0.003  o""  0004  mm.  The  medullary  rays,  as  seen  in 
this  section,  are  short-celled,  each  cell  being  about  as  long  as  the  width 
of  z\  wood  cells.  They  are  without  markings  or  pits  of  any  kind,  so 
far  as  can  be  made  out. 

"  Tangential.  Owing  to  pressure  in  this  direction  the  section  is  .somewhat 
distorted  and  does  not  show  clearly  the  relative  abundance  of  the  rays. 
The  number  of  cells  entering  into  the  composition  of  the  rays,  however, 
shows  satisfactorily.  It  is  found  that  they  are  in  a  single  vertical  .series 
of  I- 1 2  cells,  the  usual  number  being  3  or  4"  (Knowlton). 

Material  silicified.    Specimen  from  a  large,  prostrate  trunk  20  feet  or  more 

in  length  and  over  4  feet  in  diameter. 
Richmond  Basin  (Trias)  south  of  Mosley  Junction,  Chesterfield  County, 

Virginia  (Knowlton). 

5.   *  •  A.  virginianum,  Kn. 

"  Transverse.  Growth  rings  not  obvious  to  the  naked  eye,  but  apparent 
micro.scopically.  The  line  of  demarcation  consists  of  only  3  or  4  mus 
of  slightly  .smaller  and  thicker-walled  cells.  [Growth  rings  obscure, 
IJ.P.I'.]  Tracheids  prominent,  with  thick  walls.  The  individual  lells 
have  a  diameter  of  0.051  mm.,  the  average  being  about  0.0375111111. 
They  are  arranged  in  radial  rows,  which  are  most  pronounced  in  prox- 
imity to  the  medullary  rays. 

"  Radial.  The  radial  walls  are  the  only  ones  bearing  bordered  pits.  1  lie 
number  of  rows  varies,  even  on  the  same  cell,  from  1-2.  When  then  i> 
but  I  row  they  occupy  the  center  of  the  cell  and  are  in  contact.    Tliev 


ARAUCARIOXYI.ON 


207 


are  then  nearly  circular  in  outline  and  have  a  diameter  of  0.0.7-0.0:  mm 
X?,„7h,r'  '  '°7  'hey  are  in  contact  and  alternate  with  each 
o  her  and  have  a  nearly  regular,  hexagonal  outline.  These  hexaironal 
pits  have  a  d.ameter  of  0.0.6-.02,  mm.  The  inner  pore  i^ very  sS 
being  only  about  .002S-.003  mm.  in  diameter  ^  ' 

"  TaHgential.  The  ray.s  are  single  and  range  from  1-27  cells  in  height  the 
average  number  being  about  10-12  "  (Knowlton).  ^    ' 

Material  silicified.    Specimen  represented  by  a  small  fragment 
From  the  Potomac  Formation  at  TaylorsviUe,  Virginia  (Knowlton). 

6.   •  •  A.  PrMwri,  Penh. 

7>tf/w'*/-.f^    Tracheids  in  regular  radial  rows,  squarish,  39x42  u  broad- 

the  walls  6.2  /.thick.    Kesin  cells  and  special  res  n  passages  wholK- 

..   ,.«?"^"S-    No  evidence  of  growth  rings  in  fradial  extent  of  f  2  mm      ^ 

ha.i,al.  Ray  cells  all  of  one  kind,  .straight  or  narrower  at  the  ends,  equal  to 

3-9  tracheids;  the  upper  and  lower  walls  thin  and  devoid  of  pits-  the 

erminal  walls  thin,  not  pitted,  curved  ;  the  lateral  walls  .show  no  struc- 

ure  through  extreme  alteration.    Hordered  pits  not  clearly  determinable 

but  probably  round  and  in  1  row.  ^  ucicniundoie, 

''"'wide"''  '*''^''  ""'""°"''  ''•'''^"y  '"'*■ !  "^«  «"s broad,  round,  about  3.  ^ 

Material  silicified. 

The  Cheyenne  (Comanche  Cretaceous)  of  the  bluff  west  of  Sun  City  Medi- 
cine  Lodge  River,  Baker  County,  Kansas,  1897  (Prosser). 

7.   •  •  A.  arizoniCttm,  Kn. 

"  Transverse.  Annual  rings  not  apparent  to  the  naked  eye,  but  under  the 
microscope  observed  to  be  present,  the  yeariy  growths  being  separated 
by  a  layer  of  2-s  tangentially  compressed  cells;  the  tracheids  in  this 
section  are  observed  to  have  moderately  thick  cell  wall.s,  and  to  be 
separated  by  small  intercellular  .spaces.  The  largest  cells  observed  have 
a  dian.-jter  of  .055  mm.  and  the  smallest  of  about  .020  mm.,  the  average 
bemg  about  .040  mm.  t  uicid^e 

"Radial  As  seen  in  this  section  the  tracheids  are  obserN-ed  to  be  long,  and 
to  be  provided  with  numerous  pores.  These  pores  or  bordered  pits 
are  usually  arranged  m  a  single  series,  and  number  40-80  or  more  on 
each  cell.  Usually  they  touch  each  other  slightly,  but  sometimes  thev 
become  a  trifle  compressed  by  actual  contact.  When  these  pores  are 
arranged  in  2  series  they  alternate  and  are  .slightly,  if  at  all,  angled  by 
mutua  pressure.  The  pores  are  rather  large,  the  average  diameter  for 
the  outer  circle  being  about  .02  mm.,  that  for  the  inner  .0040  mm  The 
medullary  rays  are  composed  of  short,  thin-walled  cells,  which,  in  some 
in^ances,  seem  to  have  been  provided  with  small,  oval  pores.  They  are 
difficult  of  demon.stration,  and  it  is  possible  that  the  granular  contents 
_  ot  the  cells  may  give  the  appearance  of  exterior  markings. 
tiini;e>,f,al.  fhis  section  demonstrates  the  presence  of  pores  or  bordered 
pits  on  the  tangential  walls,  a  circumstance  of  infrequent  occurrence 


I    ] 


308 


ANATOMY  OF  THE  C'.YMNOSPERMS 


in  the  genus  Araucarioxylon.  They  are  much  xmalle'  than  the  pores 
on  the  radial  walls,  and  are  in  a  single  or  rarely  in  2  series.  The  pores 
are  always  separated  from  each  other,  sometimes  widely  so.  The  diame- 
ter of  the  outer  circle  is  about  .0075  mm.,  and  that  of  the  inner  about 
.0027  mm.  The  medullary  rays  are  numerous  and  range  in  height  from 
1-22  cells.  It  is  possible  that  in  some  rare  cases  they  may  be  in  2 
series,  but  this  is  certainly  not  commonly  the  case.  No  resin  ducts 
have  been  detected  in  any  of  the  sections,  their  absence  being  a  well- 
known  character  of  the  genus"  (Knowlton). 

Material  silicified.  Specimens  are  represented  by  fragmenta  of  trunks 
upwards  of  20  inches  in  length  and  13  inches  in  diameter. 

Triassic  or  Lower  Jurassic  near  Fort  VVingate,  New  Mexico;  Lithodendron 
Creek  (Cretaceous?)  and  Chalcedony  Park,  Arizona  (Knowlton). 

8.  •  •  A.  Eoppertoue,  Kn. 

"  Trann>erse.  Annual  rings  very  distinct,  of  4-8  rows  of  very  thick-walled 
fall  wood.  The  .spring  wood  is  made  up  of  very  large  though  thlcl'- 
walled  cells,  which  begin  very  abruptly  at  the  fall  wood.  The  cells 
gradually  decrease  in  siie  until  the  last  5-8  rows  of  cells  are  very  thick 

»  Radial.  A.-*  the  material  has  been  very  finely  preserved,  this  .icction  shows 
remarkably  well.  The  wide  cells  of  the  .spring  wood  are  provided  with 
usually  2  longitudinal  rows  of  hexagonal  pores,  which  quite  over  the 
walls.  Occasionally,  in  cells  of  unusual  width,  the  pore-s,  while  in  2 
series,  are  only  slightly  compressed.  Usually  when  but  1  row  is  present 
they  are  hexagonal  and  occupy  the  center  of  the  cell.  The  inner  ports 
m  these  punctations  are  relatively  .small  and  .slightly  elongated  in  .i 
direction  at  right  angles  to  the  cell.s.  The  medullary  rays  as  seen  in 
this  section  are  short,  covering  the  width  usually  of  4  or  5  wood  cells 
although  occasionally  longer  and  covering  as  many  as  8  cells.  This 
are  provided  with  a  single  row  of  Ijordered  pores  so  arranged  tl.at  i 
comes  over  each  wood  cell,  or  occa.sionally  there  may  be  2  over  a  wood 
cell.     I  he  inner  pore  is  minute. 

"  Tangential.  The  medullary  rays  as  .seen  in  this  section  are  quite  numer- 
ous, in  a  single  series  of  from  3  to  .sometimes  as  many  as  1 5  superim- 
posed cells.  The  wood  cells  as  seen  in  this  section  do  not  seem  to 
have  been  provided  with  punctations  or  other  markings"  (Knowlton) 

Material  silicified. 

Cretaceous  formation  of  the  Black  Hills,  Cycad  bed  2  miles  southeas'  of 
Minnekahta  Station,  South  Dakota  (Knowlton). 

9.   •  •  A.  Edvardianum,  Dn. 

"Trunks  with  distinct  rings  of  growth,  and  with  a  central  pith  no< 
observed  to  have  transverse  lamin.-e.  Wood  cells  with  i  or  rarelv  2  rows 
ot  contiguous,  he-vagonal  areolx.  Medullary  rays  simple,  infrequent,  with 
2-10  rows  of  cells  superimposed "  (Dawson). 

Triassic  of  Prince  Edward  Island  (Dawson). 


GINGKO 


309 


II.  GINGKOALES 

Wood  nonreslnous,  the  tracheids  of  two  kinds,  intewpcrwd.    Wood  paren- 
chyma present  and  forming  idioblasts  containing  sphere  crystals. 

I.   •  OIKOKO,  Ka.mi'K.    Plates  18  and  19 
Trantverse.  Growth  rings  broad.    The  summer  wood  thin ;   the  ."Structure 
"  ?^".  »*"'°"K*'o"t;   tracheids  chiefly  sc|uari.sh  anU  large,  with 
81  thicker-walled  tracheids  interspersed.    Ke.sin  passages  and  resin 

X.  vw  '\r"'^'  ?■  *''"""«    Cr>.stal-bearinK  idio».Ia.sts  rather  numerous 
Radtal.  Medullary  rays  devoid  of  tracheids.    Terminal  walls  of  the  ray  cells 
very  thin  and  not  pitted.    Hordered  pits  in  1-2  series.    Spiral  tracheids 
wholly  wantmg.  "^ 

^""Cwalled"'^"""  "^''  **'°"^  wan'iniiC     Kay  cells  rather  broad  and 

1.   0.  biloba,  Linn. 

Afaidtnlmir  Tree.     Salisburin.     Cinato.    Jap.  =  /cho 

Transversa.  Growth  rings  ver>-  broad,  the  summer  woo<l  ver>-  narrow  and  of 
open  structure,  passing  gradually  into  the  spring  wood.  Spring  wood 
open,  the  tracheids  large,  squarish,  very  unequal,  somewhat  thin-walled 
with  which  are  interspersed  less  numerou.s,  much  smaller,  rounded,  and 
thick-walled  tracheids.  Idioblasts  containing  sphere  crystals  somewhat 
numerous.  Medullary  rays  prominent,  slightly  resinous,  i  cell  broad 
distant  2-10,  more  rarely  15,  rows  of  tracheids.  ' 

Kadial.  Cells  of  the  medullary  rays  con.spicuously  contracted  at  the  ends 
locally  somewhat  resinous,  equal  to  about  5-7  spring  tracheids-  the 
upper  and  lower  walls  verj-  thin  and  not  pitted  ;  the  terminal  walls' very 
thin,  not  pitted  or  locally  thickened,  chiefly  straight :  the  lateral  walls 
with  oval,  bordered  pits  having  a  narrowly  oval  or  oblong  orifice,  about 
1-4,  or,  in  the  marginal  cells,  7,  per  tracheid.  Hordered  pits  very  numer- 
ous in  the  broader  tracheids,  where  they  are  compres.sed  vertically  and 
crowded  m  i  row,  or  more  generally  in  pairs,  forming  2  compact  .series; 
in  the  narrower  tracheids  few,  round,  distant,  and  often  wanting  Pits' 
on  the  tangential  walls  of  the  summer  tracheids  numerou.s,  large,  and 
open  Idioblasts  round  or  oblong,  1  sphere  crjstal  to  each  ;  scatterini: 
or  often  in  vertical  .series. 

Tangential.  Fusiform  rays  wholly  wanting.  Rays  strictly  I -.seriate,  low  to 
medium :  the  cells  rather  broad,  oval,  thin-walled,  somewhat  variable 
Idioblasts  oblong,  in  vertical  series, 

Native  of  Japan,  now  widely  distributed   through  cultivation  in  similar 
climates. 

2.    «  •  G.  pusilla,  Dn. 

Transverse.  Growth  rings  obvious,  the  spring  wood  pa.ssing  gradually  into 
the  not  strongly  defined  summer  wood:  tracheids  in  regular  radial 
rows,  very  uniform,  those  of  the  spring  wood  about  22  x  21  ^  the  walls 
5-3  Ik,  thick.    Medullary  rays  ver}-  narrow. 


fl 


3IO 


ANATOMY  OF  THE  OYMNOSPERMS 


t  ^'*1""»'y  •?>?•,  ^«T  '•"*•  "**  «"»  »«"'«»•».  "bout  17  M  high  eoual 
o  about  s  tracheid,;  the  upper  and  lower  walU  thin  and^  nof  pit?H 
the  termina    wall.-,  thin.  MraiKht.  and  devoid  of  pit.;  the  lateral  wll' 

''""Cd  '^'''"""'^  "*■'  '■3'  ■""'•  '"«'y  ^' ""- »«'«»'.  »bout  8.7  M 

Material  calcified. 

Upper  Cretaceous  of  Port  McNeil,  Vancouver  Inland,  and  Upper  Creta- 
ceou.  of  Cumshava  Inlet.  Queen  Charlotte  Lnlands. 


III.  CONIFERAI.ES 

./ooa  more  or  less  re.,inou».  often  characterized  by  the  presence  of 
.spec.al.zed  re.sin  cells,  cysts,  or  passages.  Trachcids  (transverse)  in  radial 
rows,  l^arinK  on  their  radial  wall.,,  as  al.«  on  the  tangential  walls  of  the  sum- 
mer  tniche.d.s,  round  or  elliptical,  often  distant,  bordered  pits  in  1-3  series. 

1.   TORR£YA,  Arnott.     I'latks  20  ano  21 

7><t«jT'mr  Growth   rings   rather  thin,  often   variable;   tracheids   rather 
large,  chiefly  squarish,  the  structure  generally  open    hroughout     Sum 

wa^ti^r^  '  '"^  *""■    '*"'"""'•  ''"'"•■""  p"-«" -hoTy 

"""tpirair^t':  .S'**"^'  "'  '"•^'"'''  °'  '""^  ""^  ^'^"^  -*"  »•-" 
^""CiSng.'**^  """  '*'*'"•  ^™'*">'  "^"^  °'  °»''°"«-     f  «'^'^™  ray"  -holly 

SvNOPSis  OF  Species 

A.  Summer  wood  thin,  of  2-4  tracheids  or  more,  often  double  •  the 
structure  of  the  growth  ring  very  open  throughout 
Tracheids  large,  distinctly  squarish. 
Spirals  in  2  .series. 

I.  T.  taxifolia. 

B.  Summer  wood  thin  but  sometimes  equal  to  the  spring  wood 

^ofl'^fn   '''^-  ""'T'"'  ""'   •^""•"Pi^-o""'')-  squarish,  chiefly  hexagonal, 
otten  in  very  irregular  rows. 

Spirals  imperfectly  2-4  seriate,  often  very  incomplete. 

2.  T.  californica. 
Sp.rals  in  double,  triple,  or  quadruple  series. 

3.  T.  nucifera. 


TORREYA  211 

1.  T.  taxifelk,  Amott 

Stimt$ng  CeJar.     Savin 

TraHs.,tr,t.  Growth  ,%»  variale.  i? -3  mm.  thick.  Summer  wood  of  j  x 
or  more  trache.d^^ually  very  thIn.  often  double  and  pT^inK^adualW 
no  the  HpnnKWond;  .prinx  tracheid»  «,uari.h  and  in  4ular  row, 
a  V  r.v  •  J"^"'^«"«  "'  «he  growth  rin^  o,H:n  throughout     Medu-' 

Radial  Ray  cclis  utraiKht;  the  upper  and  lower  wallH  thick  consDir..n...iv 
pnted  uniform  ;  the  terminal  walls  thin  and  entire  ^eS  cur""?- 
trtT\t  """i'"  *"*•  ■""""•  '"""*'•  ''"'  ^"''^We  pit.  with  a  diH  incJ 
boKier.  the  or.fice  ver>.  narrow.  2-5  per  tracheid.  Bordered  pitrn, 
or  2  rowH^  P.tH  on  the  tanRential  walls  of  the  .summer  tracheids  o|«cure 
Spirals  of  the  tracheids  in  2  series,  distant  5-30  m.  very  flat  the  anJui 
70.4».  compact  and  finally  ves-      -,|  in  the  summerw,^        '  *^'' 

Cied      ^^"  "  ■  *'  '       *■**"  •■"'"•  °^"'-  «'  "blonK.  thick. 


Very  durable  in  the  soil. 

Relative  specific  gravity  .... 
Approximate  fuel  value  .... 
F,?*,*^!''"*  °'  ^'a^l'city  in  kilograms  on  millimeters. 


0.5145 
5i.o« 
821. 


Ultimate  tran.sverse  strength  in  kilograms  ,,o" 

Ultimate  resistance  to  longitudinal  cru.shing  in  kilograms  li^i 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  jf^" 

(Sargent)  •     •     .  2523. 

Western  Florida. 

2.  T.  californica,  Torr. 

Stinking  Cidar.     California  Nutmeg 

Transverse.  Growth  rings  1.5-2.5  mm.  broad.    Summer  wood  thin,  some- 

fK.i  •/""'''"'■.  "^  '*''=  K'°*'*'    "»«■''   ^=»'her  open   throuuhouT 
the  tracheids  somewhat  rounded  and  in  more  or  less  irregular  row  ' 

umI  '"^'^  ""*"  ^■■°"'"'^"*' ' ""  ^"'''  '''•^'='"'  -'-M  rLr^f 

/•Ww/  Ray  cells  straight ;  the  upper  and  lower  walls  rather  thin  con- 
spicuously double  and  frequently  pitted  ;  the  terminal  wal  s  v  r^  thin 
and  entire  ;  the  lateral  walls  with  rather  variable,  round,  bordered 
pits,  1-6  per  tracheid,  the  orifice  very  narrow.  Bordered  pits  usuallv 
somewhat  d.stant,  elliptical,  in  ,  n/w,  .sometimes  in  pairs  Pt"  on 
the  tangential  walls  of  the  summer  tracheids  smaP  and  obscure 
spirals  of  the  tracheids  high,  often  very  incomplct.-iy  developed 
mperfectly  2-4  senate,  distant  5-125  /x  or  more,  the  angle  46  2^.' 
the  summer  wood  obscure  and  finally  ob.solete 

rangenlial.  Rays  medium  to  low,  the  cells  large,  rather  thin-walled 


Si   .■ 


i 


212  ANATOMY  OF  THE  GYMNOSPERMS 

Very  durable  in  the  soil. 

Relative  specific  gravity 0.4760 

Approximate  fuel  value 46.06 

Coefficient  of  ela.sticity  in  kilograms  on  millimeters      .     .  401! 

Ultimate  transverse  strength  in  kilograms       249. 

Ultimate  resistance  to  longitudinal  cru.shing  in  kilograms  5625. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  1962 
(Sargent) 

Mendocino  County,  California,  and  along  the  western  slope  of  the  Sierra 
Nevadas  to  Tulare  County,  at  elevations  of  3000-5000  feet  (Sargent). 

3.   T.  nuciiera,  Sieb.  et  Zucc. 

Trans7>erse.  Growth  rings  rather  narrow  ;  the  tracheids  of  the  spring  wood 
large,  often  distinctly  squarish,  passing  gradually  into  the  con.spicuous 
but  narrow  summer  wood  of  about  10  tracheids,  which  again  becomes 
equal  to  the  spring  wood.  Medullary  rays  prominent,  i  cell  wide,  dis- 
tant 2-10  rows  of  tracheids. 

Radial.  Cells  of  the  medullary  rays  not  contracted  at  the  ends,  equal  to 
about  6  tracheids ;  the  upper  and  lower  walls  medium,  remotely  and 
obscurely  pitted ;  the  terminal  walls  thin,  not  pitted  or  locally  thick- 
ened, diagonal  or  straight,  rarely  curved  ;  the  lateral  walls  with  small, 
conspicuously  bordered,  oval  pits  with  a  diagonal,  linear-oblong  ori- 
fice, about  2-6,  or,  in  the  summer  wood,  1  per  tracheid.  Bordered 
pits  in  I  series,  or  in  pairs,  forming  2  imperfect  scries,  distant, 
the  outer  margin  rather  ob.scure,  the  orifice  lenticular  and  diagonal 
throughout.  Pits  on  the  tangential  walls  of  the  summer  wood  wholly 
wanting.  Spirals  of  the  tracheids  prominent,  distant  5-25  ^,  in  double, 
triple,  or  quadruple  .series,  the  angle  70.5°,  in  the  sumn  er  wood 
becoming  vestigial  in  the  outer  tracheids. 

Tangential.  Rays  numerous,  low  to  medium,  the  walls  of  the  cells  rather 
thick.    Pits  on  the  tangential  walls  of  the  summer  wood  wanting. 

Japan. 

2.   ♦  TAXUS,  TouRN.     Plates  22  a.nd  23 

Transverse.  Growth  rings  variable,  often  unconformable.  The  summer 
wood  dense  and  conspicuous,  though  often  very  thin  ;  the  tracheids 
small  throughout  and  more  or  less  rounded,  the  structure  .somewh.ii 
dense  or  more  rarely  open  (T.  tloridana),  with  large  and  squarish 
tracheids.    Resin  passages  and  resin  cells  wholly  wanting. 

Radial.  Spirals  of  the  tracheids  rather  close,  2-,  rarely  3-.seriate. 

Tangential.  Ray  cells  narrowly  oblong.    Fusiform  rays  wholly  wanting. 


Synopsis  of  Species 

A.  Tracheids  .small,  rounded,  thick-walled 
Rays  low,  1 -seriate. 

Growth  rings  variable,  sometimes  double. 

2.  •  T.  canadensis,  Willd. 


TAXUS 

Rays  chiefly  hiKh,  1-2  seriate. 
Growth  rings  usually  broad. 

3.  T.  brevifolia,  Nutt. 

B.  Tracheids  medium,  rather  thick-walled 
Rays  medium. 

Growth  rings  usually  rather  broad. 

4-  T.  cuspidata,  Sieb.  et  Zucc. 
;.".  Trachci'Li  !  r  e,  the  structure  open 
Rays  chiefly  hi  ,1. 

I.  T.  floridana,  Nutt. 


213 


1.  T.  floridana,  Nutt. 

Yeio 

Transverse.  Growth  rings  medium,  irregularly  eccentric.  Summer  wood 
very  thin,  upwards  of  10  tracheids  thick,  rarely  double,  open  ;  the 
tracheids  unequal  in  irregular  rows  with  more  or  less  conspicuous 
intercellular  .spaces ;  transition  to  the  -spring  wood  gradual.  Medul- 
lary rays  prominent,  i  cell  wide,  distant  1-10  rows  of  tracheids. 

Radial.  Ray  cells  straight,  rather  narrow  ;  the  upper  and  lower  walls 
entire,  more  or  less  sinuately  unequal ;  the  terminal  walls  thin  and 
not  pitted  ;  the  lateral  wails  with  somewhat  conspicuously  bordered 
oval  or  rounded  pits,  the  orifice  lenticular,  diagonal,  chiefly  1-2, 
more  rarely  3,  or,  in  the  marginal  cells,  4  per  tracheid.  Bordered  pits 
very  scattering  except  at  the  ends  of  tracheid.s,  where  they  become 
more  or  less  2-rowed.  Pits  on  the  tangential  walls  of  the  summer 
wood  small,  often  very  distant,  the  orifice  bell-shaped.  Spirals  of 
the  tracheids  prominent,  rather  flat,  2-seriate,  distant  7.5-20  /ix,  rarely 
more,  the  angle  78.4°!  wanting  in  the  outer  summer  wood. 

Tatii^ential.  Rays  medium  to  high,  the  cells  very  narrowly  oval  to  oblong. 

Western  Florida. 

2.  •  T.  canadensis,  Willd. 

American  Ye-.v.     CrounJ  Hemlock 

Transverse.  Growth  rings  narrow  and  variable,  often  unconformable. 
Summer  wood  variable,  now  thin  and  abruptly  pa.ssing  into  the 
spring  wood,  or  thickish  and  finally  equal  to  the  spring  wood  into 
which  it  gradually  passes  ;  rather  dense.  Spring  wood  more  open,  the 
tracheids  small  throughout  and  thick-walled  but  distinctly  rounded 
and  variable.  Medullary  rays  1  cell  wide,  not  very  prominent,  dis- 
tant 2-15  tracheid.s. 

Radial.  Ray  cells  equal  to  about  5  spring  tracheids;  the  upper  and  lower 
walls  rather  thin,  uniform,  entire,  or  remotely  pitted  ;  the  terminal  walls 
thin  and  entire,  often  curved  ;  the  lateral  walls  with  round,  bordered 
pits,  1-2  per  tracheid.  Bordered  pits  small,  round.  Pits  on  the  tangen- 
tial walls  of  the  summer  wood  very  numerous  but  small  and  obscure. 
Spirals  of  the  tracheids  very  prominent,  2-3  .seriate,  distant  7.5-15  /*. 
the  angle  72.4°,  con.spicuous  throughout  the  summer  wood. 

Tangential.  Rays  very  low,  the  cells  rather  thick-walled. 


i 


if 


214 


ANATOMY  OF  THE  GYMNOSPERMS 


Damp  woodlands  fiom  Newfoundland  westward  to  Lake  Winnipeg  and 
Minnesota,  northward  to  York  Factory,  and  southward  to  New  Jersey 
or  along  the  Alleghenies  to  Virginia. 

The  Pleistocene  of  the  Don  River,  Toronto ;  Solsgirth  and  Heart  Hill, 
Rolling  River,  Manitoba,  and  Fort  Madison,  Iowa ;  Cape  Breton  and 
Bloomington,  Illinois.  An  abundantly  represented  and  widely  di.s- 
tributed  species  in  the  northern  United  States  and  southern  Canada. 

3.  T.  brevifolia,  Nutt. 
Veiv.     Western  JVw 

rrann>erse.  Growth  rings  thick,  upwards  of  2-3  mm.  Summer  wood 
dense,  about  equal  to  the  spring  wood  into  wliich  it  pa.sses  very 
gradually.  Spring  wood  open,  the  tracheids  in  regular  row.s,  rather 
uniform,  not  much  rounded.  Medullary  rays  1  cell  wide,  distant 
about  1-17  rows  of  tracheids. 

Radial.  Ray  cells  very  long  ;  the  upper  and  lower  walls  thicki.sh,  unequal 
conspicuously  double,  entire  or  distantly  pitted  ;  the  terminals  walls 
thin  and  entire;  the  lateral  walls  with  round,  con.spicuously  bordered 
pits,  chiefly  2,  more  rarely  4,  per  tracheid,  the  narrow  diagonal  orifice 
equal  to  the  outer  ring.  Bordered  pits  round  or  elliptical.  Pits  on 
the  tangential  walls  of  the  summer  tracheids  numerous  but  very  small 
and  obscure.  Spirals  of  the  tracheids  prominent,  2-.seriate,  distant 
7-5-20  ^  rarely  more,  the  angL  63.0°,  vestigial  in  the  summer  wood. 

langential.  Rays  commo.^lv  high,  the  cells  thick-walled. 

Very  durable  in  the  soil. 

Relative  specific  gravity 

Approximate  fuel  value .     .     .     . 

Coefficient  of  ela.sticit    in  kilograms  on  millimeters      '.     .  ^u. 

Ultimate  tran.sverse  strength  in  kilograms 460. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  7734 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  A-^-y% 

(Sargent)                                                         *                    "  ^~'^' 

Vancouver  Island  and  adjacent  mainland  and  on  the  lower  Skeena 
(Macoun)  ;  .sparingly  in  the  Queen  Chariotte  Islands  (Dawson)  ;  .south- 
ward through  the  coast  ranges  of  Briti.sh  Columbia,  Wa.shington,  ami 
Oregon,  the  western  slopes  of  the  Rocky  Mountains  in  Montana,  and 
through  the  California  coast  ranges  to  Monterey  and  the  southern  .slopes 
of  the  Sierra  Nevadas  to  latitude  37°  N.  (Sargent). 


0.6391 
63.78 
761. 


T.  cuspidata,  Sieb.  et  Zucc. 
Yew.    Jap.  =  Araragi 

Summer  wood  prominent,  about 


Trans7'erse.  Growth  rings  rather  broad.    __ 

one  fourth  the  spring  wood  into  which  it  passes  gradualTy  "sprrn" 
wood    somewhat    open,   the    tracheids  distinctly   hexagonal,   rather 


THUJOPSIS  215 

uniform  and  thin-walled.  Bordered  pits  on  ilie  tangential  walls  of  the 
summer  tracheids  few  and  obscu-e.  Medullary  rays  prominent,  1  cell 
wide,  distant  about  2-10  tracheids.  -       -     ■ 

RadiaL  Cells  of  the  medullary  rays  not  much  contracted  at  the  ends  • 
the  upper  and  lower  walls  rather  thin,  but  very  une.iual  and  obscurely 
^u-'l  '  'j'^!"'"'"^l  «:>lls  thin,  often  obscure,  not  pitted  or  locall'y 
thickened,  diagonal  and  chiefly  straight;  the  lateral  walls  with  con- 
spicuously  bordered  pits,  oval,  with  a  diagonal,  knticular-oblong 
orifice,  chiefly  2  per  tracheid  in  radial  series,  equal  to  about  4-0 
tracheids.  Bordered  pits  round,  about  two  thirds  the  width  of  the 
tracheid,  m  open  rows,  the  orifice  round,  concentric,  in  the  summer 
wood  becoming  lenticular,  diagonal.  Pits  on  the  tangential  walls  of 
the  summer  tracheids  distant,  rather  ob.scure.  Spirals  of  the  tracheids 
2-seriate,  distant  12.5-25  ,*,  the  angle  66.  i",  vestigial  in  the  .summer 

Tangential.  Bordered  pits  on  the  tangential  walls  of  the  summer  tra- 
cheids not  very  numerous,  in  distant  groups.  Rays  low  to  hiuh 
numerous.  *  ' 


% 


3.  THUJOPSIS,  SiEB.  ET  Zucc.    Plates  24  and  25 

Transi>erse.  Growth  rings  usually  very  narrow.  Resin  passages  wholly 
wanting.    Resin  cells  not  numerous  but  prominent,  rarely  zonate 

Kadtal.  Ray  tracheids  wholly  wanting.  Bordered  pits  generally  rather 
numerous,  in  i  row.    Tracheids   wholly   without   spirals 

Tangential.    Fusiform  rays  wholly  wanting,  the  i-seriate  rays  low,  resinous 


1.  T.  dolabrata,  Sieb.  et  Zucc. 

Jap.  =  Ilibii 

Transverse.  h   rings  very   narrow   and   variable.     Summer   wood 

rather  ,  retimes  dense,  thin,  of  2-10  tracheid.s,  the  transition 

to  the  ood  rather  gradual.    Spring  wood  very  open,  the 

trachtids  uge,  squari.sh-hexagonal,  in  very  regular  rows,  uniform, 
very  thm-walled.  Resin  cells  very  prominent,  not  numerous,  scatter- 
ini;  throughout  the  growth  ring,  not  obviously  zonate.  Medullary 
rays  prominent  and  resinous,  not  numerou.s,  i  cell  wide,  di.stant  ^-1^ 
or  sometimes  16  rows  of  tracheids. 

Radial.  Rays  somewhat  resinous.  The  cells  conspicuou.sly  contracted  at 
the  ends,  equal  to  5-6  spring  tracheids;  the  upper  and  lower  walls 
thick,  sparingly  pitted ;  the  terminal  walls  thin,  often  curved,  not 
pitted  or  locally  thickened ;  the  lateral  walls  with  .small,  obscurely 
bordered  pus,  the  large  orifice  broadly  lenticular  or  oval,  about  \--> 
per  tracheid.  Bordered  pits  round  or  elliptical,  nearly  as  broad  as 
the  tracheid,  rather  numerous,  in  1  row.  Pits  on  the  tangential  walls 
of  the  summer  tracheids  few,  very  flat,  and  rather  obscure.  Re.sin  cells 
15-25  /u  wide,  chiefly  225  /i  long. 

Tangential.  Rays  low,  not  very  broad,  resinous ;  the  cells  oval  or  oblong, 
rarely  round,  rather  thick-walled,  1 -seriate. 


4 

V. 


f 


2l6 


ANATOMY  OF  THE  GVMNOSPERMS 


4.  CRYPTOMERIA,  Don.    Plates  26  and  27 

Trannierse.  Growth  rings  medium,  with  a  dense  summer  wood  and  open 
spring  wood.  Resin  passages  wholly  wanting.  Resin  cells  prominent 
and  scattering. 

Radial.  H^y^  wholly  devoid  of  tracheids;  the  cells  sparingly,  if  at  all 
resinous;  the  terminal  walls  thin  and  not  pitted  or  locally  thickened 
Bordered  pits  in  1  row,  much  less  than  the  diameter  of  the  tracheid 

Tangential.  Fusiform  rays  wholly  wanting.  Cells  of  the  I -seriate  rays  rather 
broad,  round. 

1-  C.  japonica,  Don. 

Cryptomeria.    Jap.  =  Sugi 

Transverse.  Growth  rings  medium,  rather  uniform.  The  summer  wood 
prominent,  about  one  fourth  the  spring  wood  into  which  it  passes 
rather  abruptly,  the  structure  dense.  Spring  wood  very  open  the 
large  tracheids  hexagonal,  uniformly  thin-walled.  Resin  cells  promi- 
nent and  scattering,  chiefly  confined  to  the  summer  wood  and  the 
late  spring  wood,  the  resin  6"ing  the  cells.  Medullary  rays  some- 
what  prominent,  distant  2-.,       ire  rarely  20,  rows  of  tracheids. 

Radial  Ray  cells  more  or  less  conti.  '  ..  .ne  ends,  equal  'o  s-9  spring 
tracheids;  tne  upper  and  lower  w..;s  rather  thick,  uniform,  distantly 
pitted;  the  terminal  walls  thin,  not  pitted  or  locally  thickened, 
straight  or  curved  ;  the  lateral  walls  with  round,  ob.scurely  bordered 
pit.s,  1-2  ,n  radial  series  or  in  the  marginal  cells  3-5  per  tracheid 
Bordered  pits  one  half  the  diameter  of  the  tracheid,  in  1  row,  round! 
the  orihce  round  ;  in  the  summer  wood  small,  becoming  obscure  or 
entirely  wanting,  the  orifice  a  slit.  Pits  on  the  tangential  walls  of  the 
summer  tracheids  small  but  numeious.  Resin  cells  upwards  of  20  u 
wide  and  upwards  of  400  fi.  long. 

Tangential  Rays  all  i -seriate,  rarely  2-seriate  in  part ;  low,  the  cells  round, 
rather  thick-walled,  uniform. 


5.  PODOCARPUS,  L'Her.    Plates  28  and  29 

Trans^'erse.  Growth  rings  very  variable,  either  very  narrow  or  very  broad 
bum...er  wood  very  thin  and  not  clearly  distinguishable  from  the- 
spring  wood.  Structure  open,  tracheids  of  the  spring  wood  lart;f 
squarish.  Resin  passages  wholly  wanting.  Resin  cells  numerous,' 
scattering,  rarely  zonate. 

Radial  Ray  tracheids  wholly  wanting.  Bordered  pits  small,  distant  in 
I  row.    Spiral  tracheids  wholly  wanting 

Tangential  Fusiform  rays  wholly  wanting.  Ray  cells  oval  or  round, 
thick-walled. 

1.  P.  macrophylla,  Don. 

y,;/.  =  Maki 
Transverse.  Growtn  rings  very  variable  and  narrow,  or  again  broad.    The 
summer  wood  very  thin  and  not  very  different,  of  2-4  tracheids  and 
passing  imperceptibly  into  the  spring  wood.    Tracheids  of  the  spring 


TAXODIUM 


217 


n^S.^'^'f."*''"*'''"'^"''''''  ""^^  ""if""",  •-'nd  somewhat  thick-walled. 
Kes  n  lells  very  numerous,  the  resin  rhiefly  in  a  peripheral   Jayur  • 

oHe«z^nl^:°"''M°H ','.''"  «'°""'  ""«  "^  occasionally  becoming  more 
or  ess  zonate.  Medullary  rays  prominent,  numerous,  and  i  cell  wide 
distant  2-9  rows  of  tracheids.  ' 

Radial.  Medullary  rays  conspicuously  resinous,  numerous ;  the  cells  not 
muchcontractedat  the  ends,  equal  to  about  6  tracheids.    The  uppe 
and  lower  walls   thickish,  unequal,  irregulariy  and  often   distant^ 

S'!h-  f''r'i^''.'''°"'*'  '^^  '^™'"^'  «■•■»"''  «hi"  not  pitfed  or 
Sr'^nt'.  "''^'  '^'"^  '''^"Sly  curved  ;  the  lateral  walls  wfth  smaj 
rather  obscure,  oval  pUs,  1-2  per  tracheid,  theorif^.e  narrowly  lenticu 

la^  often  shtl.ke  Resin  cells  very  numerous,  upwards  of  20 /wide  Ind 
200  ^  long.    Bordered  pits  small,  round,  distant  in  .  row.    Pii.  on  the 

rJS  Thr."'  ""■   '^^  '"""""  "°«*^  ""'""°"^'  conspicuous,  open 
rangenhal.  The  i -senate  rays  very  numerous,  medium  ;  the  ovalor  round 
cells  somewhat  thick-walled,  rarely  in  pairs. 

6.  •  TAXODIUM,  Rich.    Plates  30  and  31 

Tratt^n>erse  The  suminer  wood  of  the  usually  broad  growth  rings  much 
less  than  the  spring  wood.  Resin  passages  wholly  wanthi^  Hesin 
cells  numerous  and  prominent,  either  scattering  or  zonate 

RadiaL  Rays  wholly  without  tracheids,  the  cells  commonly  contracted  at 
the  ends.    Tracheids  wholly  without  spirals  i-""iraciea  at 

^'"'•broadly  oval.^"™  "^'  '^''""^  ''^"*'"^*  "*'  ""^  °^  ">«  -««"=''«  «>- 

Synopsis  of  Species 
Resin  cells  large,  numerous,  more  or  less  distinctly  zonate 

Pits  on  the  lateral  walls  of  the  rays  cells  1-4,  mo.*  rarely  7,  per  tra- 
cheid, the  lenticular  orifice  narrow. 

Bordered  pits  numerous,  often  paired,  or  in  the  eariier  spring 
wood  imperfectly  2-rowed. 

1.  *  T.  distichum. 

Resin  cells  obscure  and  forming  an  open  zone  on  the  inner  face  of  the 
summer  wood. 

Pits  on  the  lateral  walls  of  the  ray  cells  about  2-3  per  tracheid  in 
radial  series. 

Bordered  pits  numerous.in  the  eariier .springwood  crowded  into  2-3 
compact  rows,  but  becoming  2-rowed  toward  the  summer  wood. 

2.  •  *  T.  laramianum. 

1.  •  T.  distichum,  Rich. 
Bald  Cypress.     DeciUuotis  Cypress 
Transverse.  Growth  rings  usually  very  broad.    The  dense  and  conspicu- 
ous summer  wood  often  double  or  treble;  transition  to  the  spring 


2l8 


ANATOMY  OF  THE  GYMNOSPERMS 


wood  somewhat  gradual.  Spring  wood  very  open ;  the  tra(  hekls 
very  large,  thin-walled,  hexagonal,  rather  uniform.  Resin  cells  nuim  r 
ou.s,  large,  not  strongly  resinous,  distinctly  zonate  or  sometimes  .scat- 
tering throughout  the  growth  ring.  Medullary  rays  prominent  hut 
sparingly  resinous,  distant  2-.S  or  more  rarely  13  rows  of  tracheids, 
1  cell  wide. 

Radial.  Ray  cells  sparingly  resinous,  usually  more  or  less  contracted  at 
the  ends,  equal  to  3-5  .spring  tracheids ;  the  upper  and  lower  walls 
thickish,  rather  unequal  and  entire  or  distantly  and  often  imperfectly 
pitted  ;  the  terminal  walls  thin,  .sometimes  obscure,  often  curved,  not 
pitted  or  locally  thickened  ;  the  lateral  walls  with  prominent  and  con- 
spicuou.sly  bordered  pits,  round,  1-4,  or  more  rarely  7,  per  tracheid, 
the  very  narrow,  lenticular  orifice  often  as  long  as  the  outer  limits 
of  the  pit.  Bordered  pits  chiefly  elliptical,  numerous,  variable,  often 
paired  and  in  the  earlier  spring  wood  becoming  imperfectly  2-seriate. 
Pits  on  the  tangential  walls  of  the  summer  tracheids  very  numerous, 
not  very  large.  Resin  cells  sparingly  resinous,  25  /x  wide,  chiefly 
140  ft.  long,  but  ranging  upwards  of  310  /n. 

Tangential.  Rays  numerous,  medium  to  high,  very  sparingly  resinous ;  the 
round  or  oval  cells  rather  broad  and  thick-walled,  rarely  in  pairs. 

Wood  very  durable  in  the  soil  and  of  great  economic  value. 

Relative  specific  gravity 0.4543 

Approximate  fuel  value 45.24 

Coefficient  of  elasticity  in  kilograms  on  millimeters  .     .     .  1032. 

Ultimate  transverse  strength  in  kilograms 291. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  .  6771. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms       .     .  1166. 
(Sargent) 

Material  silicified. 

Delaware  to  Florida  and  westward  through  the  Gulf  States  to  Texas;  north- 
ward through  Tennessee,  Kentucky,  and  southern  Missouri  to  southern 
Illinois  and  Indiana  (Sargent). 

This  well-known  Tertiary  plant,  chiefly  represented  by  its  foliage  and  fruit, 
is  known  through  its  woody  structure  in  only  one  instance,  occurring  in 
the  Eocene  of  the  Porcupine  Creek  and  Great  Valley  groups. 


2.  •  *  T.  laramianum,  Penh. 

Transverse.  Growth  rings  prominent,  rather  broad.  Summer  wood  promi- 
nent, upwards  of  17  tracheids  thick  and  passing  somewhat  gradually 
into  fhe  broad  spring  wood.  Spring  tracheids  large,  squarish-hex- 
agonal, thin-walled,  uniform  in  regular  rows.  Resin  cells  obscure  and 
fornv"g  an  open  zone  on  the  inner  face  of  the  summer  wood.  Rtsin 
passages  wholly  wanting.  Medullary  rays  numerous,  narrow,  distant 
about  2-8  rows  of  tracheids. 

Radial.  Medullary  rays  wholly  devoid  of  tracheids.  Ray  cells  straii^tit, 
equal  to  about  3  tracheids ;  the  upper  and  lower  walls  rather  thick 


LIBCCEDRUS 


219 


and  sparingly  pitted  ;  the  terminal  walls  straight  or  diagonal,  some- 
times  cur\ed,  entire  ;  the  lateral  walls  with  oval  or  rounded  pits,  about 
2-3  per  tracheid  in  radial  series.  Bordered  pits  numerous,  •  becom- 
ing 2-rowed  toward  the  summer  wood,  though  distinctly  crowded  into 
2-3  compact  rows  in  the  earlier  spring  tracheids.  Kesin  cells  not 
conspicuous. 
Tangential.  Resin  cells  conspicuous  but  not  numerous,  about  3  times 
longer  than  broad.  Medullary  rays  rather  numerous  and  narrow 
often  very  high,  strictly  i-seriate ;  the  cells  oval,  more  rarely  round 
in  the  low  rays. 

Material  siliciiied. 

A  distinctive  species  occun'ng  in  the  Laramie  (Eocene)  at  Cochrane, 
Alberta. 


7.  LIBOCEDRUS,  Endl.    Plates  32  and  33 

Transverse.  The  thin  and  rather  dense  summer  wood  usually  showing  a 

more  dense  median  layer.    Resin  passages  wholly  wanting.    Re.sin 

cells  numerous  and  conspicuously  zonate. 
Radial.  Rays  wholly  without  tracheids.    The  terminal  walls  of  the   ray 

cells  straight  or  curved,  entire,  locally  thickened  or  even  coarsely 

pitted.    Tracheids  wholly  without  spirals. 
Tangential.  Fusiform  rays  wholly  wanting,  the  rays  strictly  of  one  kind. 


1.  L.  decttrrens,  Ton-. 

White  Cedar.     Bastard  Cedar.     Post  Cedar.     Incense  Cedar 

Transverse.  Growth  rings  broad.  The  dense  summer  wood  rather  thin 
and  composed  of  8-14  tracheids,  often  more  or  less  double  ;  the  tran- 
-sition  from  the  spring  wood  gradual.  Spring  tracheids  in  regular 
rows,  uniform,  squarish,  large  and  thin-walled,  the  structure  open. 
Resin  cells  numerous,,  prominent,  large,  in  a  very  broad  band  or 
scattering  through  the  late  spring  wood.  Medullary  rays  prominent, 
numerous,  resinous,  1  cell  wide;  distant  2-8,  rarely  15,  rows  of 
tracheids. 

Radial.  Ray  cells  sparingly  resinous,  more  or  less  contracted  at  the  ends, 
equal  to  about  4-8  spring  tracheids  ;  the  upper  and  lower  walls  medium 
and  entire,  or  again  distantly  and  often  imperfectly  pitted ;  the  ter- 
minal walls  thin,  straight,  or  curved  and  locally  thickened  or  even 
coarsely  pitted ;  the  lateral  walls  with  small,  narrowly  bordered,  oval 
pits  with  a  lenticular,  diagonal  orifice,  1-4  per  tracheid.  Bordered 
pits  in  I  row,  sometimes  in  pairs,  numerous.  Pits  on  the  tangential 
walls  of  the  summer  tracheids  numerous  and  large,  extending  almost 
through  the  entire  zone.  Resin  cells  20-30  /it  wide,  chiefly  1 75-225  /n 
long,  less  commonly  upwards  of  475  /tt. 

Tangential.  Rays  very  variable,  often  2-3  seriate  at  the  center  or  near 
one  end,  sparingly  resinous,  rather  broad ;  the  cells  round  or  oval, 
uniform,  the  walls  medium. 


'I 
I 


!r 


iir. 


220  ANATOMY  OF  THE  GYMNOSFERMS 

A  lar^e  t        ^0-40  m.  in  height,  with  a  trunk  1.20-2.10  m.  in  diameter. 
The  ligl'  !  wood  is  very  durable  in  contact  with  the  soil. 

Ri            specific  gravity 0.4017 

Ai           mate  relative  fuel  value 401 4 

0       -lent  of  elasticity,  in  kilograms  on  millimeters     .     .  847. 

Ui       ate  transverse  strength  in  kilograms 291. 

Uiuinate  resistance  to  longitudinal  crushing  in  kilograms  7446. 

Resistance  to  indentation  to  i. 27  mm.  in  kilogram.s       .     .  1561. 
(Sargent) 

Santian  river,  Oregon ;  southward  along  the  western  slopes  of  the  Cas- 
cade and  Sierra  Nevada  mountains  at  elevations  of  3000-8500  feet, 
thence  through  California  Coast  Range  to  the  San  Bernardino  and  Cayu- 
maca  mountains  (Sargent). 


8.  •  THUYA,  TouRN.    Plates  34  and  35 

Transverse.  Summer  wood  thin  and  dense.  Resin  passages  wholly  want- 
ing. Resin  cells  more  or  less  prominent,  but  often  widely  scattering. 
Tracheids  chiefly  large  and  thin-walled,  squarish. 

Radial.  Ray  tracheids  wholly  wanting  except  in  T.  japonica.  Ray  cellh 
usually  conspicuously  contracted  at  the  ends ;  the  terminal  walls  thin 
and  not  pitted  or  locally  thickened,  usually  much  curved.  Tracheids 
wholly  without  spirals. 

Tanj^ential.  Fusiform  rays  wholly  wanting.  Ordinary  rays  narrow,  medium 
to  low,  strictly  i -seriate,  the  cells  chiefly  narrowly  oval  to  oblong. 


Synop.sis  of   Species 

Pits  on  the  lateral  walls  of  the  ray  cells  1-2,  or  in  the  marginal  cells  and 
low  rays  upwards  of  8  per  tracheid. 

Pits  on   the  tangential  walls  of  the  summer  wood  confined  to  the 
outermost  wall. 

3.  T.  japonica,  Max. 
Pits  on  the  lateral  walls  of  the  ray  cells  1-4,  or  in  the  marginal  cells  and 
low  rays  6  per  tracheid. 

Pits  on  the  tangential  walls  of  the  summer  wood  not  confined  to  tin- 
outermost  tracheid  wall. 

1.  T.  gigantea,  Nutt. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-4,  or  in  the  marginal  cells  and 
low  rays  7  per  tracheid. 

Pits  on   the  tangential  walls  of  the  summer  wood  confined  to  tlit- 
outermost  tracheid  wall. 

2.  *  T.  occidentalis,  Linn. 


THUYA 


3ai 


1.  T.  glgantM,  Nutt. 

Rtd  Ctdar.     Canoe  Ctdar.     n'ttttrn  White  Cedar 

Transverse.  Growth  rings  usually  broad.  Summer  wood  prominent  and 
upwards  of  14  tracheids  thick,  the  transition  to  the  sprinj;  wood 
gradual.  Spring  wood  open,  the  thin-walled  tracheids  s(|uari.sh- 
hexagonal,  rather  uniform,  in  regular  rows.  Kesin  cells  usually  in  a 
single  narrow  band  in  the  summer  wood  of  distant  growth  rings,  thus 
often  apparently  wanting.  Medullary  rays  somewhat  resinou.s,  i  cell 
wide,  distant  2-20  tracheids. 

Radial.  Rays  devoid  of  tracheids,  somewhat  resinous.  Ray  cells  con- 
spicuously contracted  at  the  ends ;  the  upper  and  lower  walls  thick- 
ish  and  entire  or  remotely  pitted  ;  the  terminal  walls  thin,  generally 
curved,  •  ot  pitt  d  or  locally  thickened  ;  the  lateral  walls  with  small, 
oval  pits  with  a  lenticular  or  oval  orifice,  1-4,  or  in  the  marginal 
cells  and  low  rays  0  per  tracheid.  Bordered  pits  round,  in  one  row, 
sometimes  in  pairs.  Fits  on  the  tangential  walls  of  the  summer  wood 
small,  conspicuous,  often  remote,  not  confined  to  the  outermo.st  wall. 
Resin  cells  about  15  /t  wide,  60-255  M  long,  very  variable,  thin-walled. 

Taiii^ential.  Rays  medium,  narrow,  the  cells  oblong. 

A  light,  soft,  and  rather  brittle  wood  which  is  very  durable  in  the  soil. 

Relative  specific  gravity 0.3706 

Approximate  relative  fuel  value 37. Qo 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  1034. 

Ultimate  transverse  strength  in  kilograms       319. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  7197. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  1114. 
(Sargent) 

Alaska,  .southward  through  the  coast  ranges  of  Briti.sh  Columbia,  where 
it  attains  to  an  altitude  upwards  of  6000  feet,  often  attaining  a  height 
of  150  feet  and  a  diameter  of  more  than  10  feet  (Macoun);  thence 
through  Washington  Oregon,  and  California,  as  far  as  Mendocino 
County,  and  eastw.u  through  Washington  and  Idaho  to  northern 
Montana  (Sargent). 

2.  *  T.  occidentalis,  Linn. 

White  Cedar.     Arbor  yHw 

Transverse.  Growth  rings  chiefly  broad  but  variable.  ummer  wood  very 
thin,  of  2-6  or  upwards  of  14  tracheids,  the  stn  ure  very  open,  the 
tracheids  large  and  squarish-hexagonal,  in  regi  ir  rows,  rather  uni- 
form, thin-walled.  Resin  cells  few  and  widely  se.ittering,  often  appar- 
ently wanting,  or  sometimes  distantly  zonate  in  the  spring  wood. 
Medullary-  rays  not  prominent,  i  cell  wide,  distant  2-15  tracheids. 

Radial.  P  lys  devoid  of  tracheids,  sparingly,  if  at  all,  resinous.  Ray  cells 
more  or  less  contracted  at  the  ends;  the  upper  and  lower  walls 
medium,  with  conspicuous  though  often  distant  pits;  the  terminal 
walls  thin,  often  strongly  curved,  not  pitted  or  locally  thickened; 


t 


m 


1  ^^^t,_ 


323 


ANAl'OMY  OF  THE  GYMwOSPERMS 


the  upper  and  lower  walls  medium,  with  conxpicunu.s,  though  often 
distant,  simple  pits;  the  lateral  walls  with  small,  oval  pitH  with  in 
oval  or  lenticular,  rather  large,  orifice,  1-4,  or  in  the  marginal  cells 
and  low  rays  7  per  tracheid.  Bordered  pits  elliptical  in  one  row,  some- 
times in  pairs,  those  of  the  summer  wood  tinally  obscure  and  wanting. 
Pits  on  the  tangential  walls  of  the  summer  wood  small,  often  obscure, 
freque  :Iy  very  distant  and  confined  to  the  outermost  tracheid  wall. 
Resin  cells  15-40  /t  wide. 
Tangential.  Rays  low  and  narrow,  the  cells  uniformly  narrow,  oblong. 

A  tree  13-18  m.  in  heig^-t  and  1.20-1.50  m.  in  diameter,  producing  a  light, 
soft,  and  very  durable  wood. 

Relative  specific  gravity 0.3164 

Approximate  relative  fuel  value 31-53 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  533. 

Ultimate  transverse  strength  in  kilograms 219. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  4903. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  957. 
(Sargent) 

Rare  in  Nova  Scotia ;  abundant  in  New  Brunswick,  Quebec,  and  Ontario, 
and  northward  to  Hudson's  Bay  ;  westward  to  Lake  Winnipeg  and  tho 
mouth  of  the  Saskatchewan  in  latitude  53"  30'  N.  (Macoun);  southward 
to  New  Jersey  and  through  the  Alleghenies  to  North  Carolina  (Britton) ; 
thence  westward  through  New  York  and  Pennsylvania  to  central  Michi 
gan,  no- 'hem  Illinois,  and  central  Minnesota  (Sargent). 

This  sjjec'  •  :s  a  well-defined  and  .somewhat  abundant  constituent  of  the 
Pleistocene  flora  in  the  Uon  Valley  at  Toronto,  and  the  Leda  clays  of 
Montreal ;  Leda  River,  Manitoba,  and  Marietta,  Ohio.  An  undescrilxd 
species  of  Thuya  also  occurs  in  the  Mgnite  Tertiary,  Saskatchewan, 
probably  of  the  Porcupine  Creek  and  Great  Valley  groups. 


3.  T.  japonica,  Max. 

Jap.  —  Xedzuko 

Transverse.  Growth  rings  rather  narrow,  variable  ;  the  prominent  summer 
wood  very  narrow,  of  about  6  tracheids,  or  again  upwards  of  16  tra- 
cheids,  rather  dense,  the  transition  to  the  spring  wood  gradual.  The 
broad  spring  wood  open ;  the  tracheids  rather  large,  con.spicuously 
hexagonal,  very  thin-walled,  in  regular  rows,  uniform.  Resin  cells 
prominent  and  dark,  few  and  widely  scattering,  chiefly  in  the  summer 
wood.  Medullary  rays  not  prominent,  sparingly  resinous  i  cell  wide, 
narrow,  distant  2-18  tracheids. 

Radial.  Rays  very  sparingly  resinous,  rarely  with  tracheids.  Cells  chiefly 
straight,  the  upper  and  lower  walls  rather  thin,  uniform,  and  fre- 
quently pitted ;  the  terminal  walls  thin,  very  commonly  curved,  not 


SKQUOIA 


223 


pitted  or  locally  thickened:  the  lateral  walU  with  small,  oval  piu, 
the  orilicc  broadly  ItiitiLular,  12  or  in  the  ni.iri;inal  cells  and  low 
rays  upwards  of  «  per  tracheid.  Bordered  pits  illiptical  in  one  row, 
sometimes  in  pairs,  numerous,  alx>ut  one  half  the  diameter  of  the 
tracheid.  Fits  on  the  tangential  walls  of  the  summer  wi"hI  confined 
to  'he  outermost  wall,  not  lar^e,  flat,  rather  numerous,  often  obscure. 
Kesin  cells  few,  12.5/1  wide,  al)aut  135  /t  lon^. 
TaHj^ential.  Hays  low  to  medium,  very  narrow,  strictly  i-seriate  ;  the  cells 
uniform    Jiin-walled,  obloi.,,. 


9.  •  SEQUOIA,  Endi..    Plates  36  and  37 

Transverse.  Growth  rings  chiefly  narrow,  the  usually  thin  summer  w(mxI 
distinct.  Resin  cysts  when  present  forming  a  continuous  row  on  thf; 
outer  face  of  distant  growth  rings.  Tracheids  large,  thin-walled, 
square.  Resin  cells  scattering,  chiefly  in  the  spring  wood,  or  more 
rarely  wholly  in  the  summer  wood  (S.  Penhallowii), 

Radial.  Rays  without  tracheids,  but  the  marginal  cells  .sometinus  crystal- 
logenous  (S.  Penhallowii).  Pits  of  the  ray  cells  with  a  narrow  border, 
the  orifice  commonly  parallel  with  the  cell  axis.  Pits  ofton  occur  on 
the  tangential  walls  of  both  spring  and  summer  tracheid.*.  Terminal 
walls  of  the  ray  cells  rarely,  if  at  all,  oitted,  except  in  S.  I  •.■nhallowii. 
Tracheids  wholly  without  spirals.  i<adial  resin  pas.sages  wanting 
except  in  S.  Burgessii  and  S.  Penhallowii,  when  they  contain  promi- 
nent thyloses. 

Taiii^enlial.  Fusiform  rays  usually  wanting,  or  present  in  S.  Burge.ssii  and 
S.  Penhallowii. 


Synopsis  ok  Species 

Resin  pa.s.sages  wholly  wanting. 

Resin   cells  more  or   less  numerous  and  scattering  throughout  the 
growth  ring. 

Bordered  pits  large,  oval,  conspicuously  in  1-2  rows. 

Ray  cells  (tangential)  of   the  spring  wood  very  large  and 
broad,  squarish. 

Pit.s   on    the   lateral   walls   of   the  rays  ceils    2-O  per 
tracheid. 

1.  S.  semperv'irens. 
Bordered  pits  in  1  or  sometimes  2  rows. 

Ray  cells  (tangential)  large,  broad,  squarish,  or  as  often 
transversely  oblong. 

5.  •  •  S.  magnifica. 
Ray  cells  (tangential)  broadly  oval  or  round. 

T'u,  on  the  lateral  walls  of  the  ray  cells  1-2,  or  rarely 
3-4,  per  U^cheid. 

2.  S.  gigantea. 


»H 


ANAFOMY  OF  THE  GYMNOSPERMS 


Rwin  cellH  on  the  outer  (ace  of  the  Hummer  wood  only. 
Bordered  pitx  not  definitely  Mriate. 

Plt»  on  the  lateral  walls  of  the  ray  cellr  i  ncriate  in  the  cen 
tral,  j-3  Mriate  in  the  manpnal  cells  which  are  crystal- 
logenous. 

6.  •  •  S.  Penhallowii. 
Re»in  paMaKPii  present  on  the  outer  face  of  the  numtner  wood. 

Resin  ccll.H  more  or  less   numerous  and  scatterinj{  throughout  the 
growth  rin>{. 

Bordered  pit.s  in  i-j  rows. 

Ray  cells  (tangential)  very  larjje  and  firoatf,  squarish. 

Pits  on  the  lateral  walls  of  the  ray  cells  2-6  per  tracheid. 
I.  S.  sempervirens. 
Ray  cells  (tanKential)  ov.il  or  round. 

Pits  on  the  lateral  walls  of  the  ray  cells  obliterated. 

3.  •  •  S.  Langsdorfii. 
Resin  passages  (radial  only)  with  thyloses. 

Resin  cells  somewhat   numerous,   scattering   throughout   the   growth 
ring  but  most  abundant  on  the  outer  face  of  the  summer  wood. 
Bordered  pits  in  1-2  rows. 

Marginal  ray  cells  not  crystallogenous. 

4.  •  •  S.  Burgessii. 

Resin  passages  (traumatic)  present,  both  vertically  and  radially. 
Resin  cells  on  the  outer  face  of  the  summer  wood  only. 
Bordered  pits  not  definitely  .seriate. 

Pits  on  the  lateral  walls  of  the  ray  cells  1 -seriate  in  the 
central,  2-3  seriate  in  the  marginal  cells  which  are  crystal- 
logenous. 

6.  •  •  S.  Penhallowii. 


1.  S.  cempenrirens,  EnUI. 

KtdwooJ 

Transverse.  Summer  wood  very  prominent,  of  3-1 1  tracheids,  or  upwards 
of  one  third  the  spring  wood  ;  the  structure  ofte'i  -.ery  open,  or  whtn 
dense  soinetimes  double.  Spring  wood  very  open,  the  large,  squarish, 
or  hexagonal  tracheids  often  radially  elongated,  the  walls  thin  ;  tran- 
sition to  the  summer  wood  rather  abrupt.  Resin  cysts  contiguous 
and  coalescent  and  forming  an  extended  tangential  series  in  the 
mitial  growth  of  the  spring  wood,  of  distant  growth  rings.  Kcsin 
cells  rather  abundant,  very  prominent  and  dark,  rather  large,  scattir 
ing  through  the  spring  \\,>od.  Tracheids  rather  uniform  in  viry 
irregular  rows.  Medullary  rays  broad,  prominent,  1  cell  wide,  distant 
I -1 2,  more  rarely  20,  rows  of  tracheids. 


SEQUOIA 


"5 


RMlml  Kay  celU  utraiKht  or  rarely  contacted  at  the  cmls.  somewhal 
resnouH,  equal  to  alwut  4  "prinK  tracht,tl»;  the  upper  and  lower 
wall!,  thin,  rather  uniform,  rarely  pittciJ ;  the  terminal  walls  vtry  thin. 
utralKht  or  curved,  and  not  pitted;  the  lateral  walln  with  lartre  oval 
naiTowly  bordered  pits.  2-6  per  tracheid,  the  round  or  hro.uUy  oMonJ 
orifice  either  parallel  with  or  diaRonal  to  thi-  cell  axis.  Bordered  uiln 
con»picuou.sly  in  1-2  row».  elliptical.  I'itn  on  the  lanKential  walU  of 
the  Hummer  \».K)d  numerous,  small,  the  orifice  l.roadly  trumiH.t-.Hhapid 
or  bell-Hhaped  ;  the  pits  on  the  tanKcntial  walls  of  the  sprinir  wood 
large,  sometimes  rather  abundant.  Resin  cell,  rather  numerous 
30-40  ^  wide,  1 75-480  /t  long. 

TaHf^eufial.  Rays  medium  to  high,  often  more  or  less  2-seriate  •  the  cells 
very  lar^e  and  broadly  oval,  tho.se  in  the  center  commonly'conspicu- 
ously  squarish.  '  ^ 

Wood  very  durable  in  contact  with  the  soil  and  of  Kre.U  economic  value 
Trees  61-92  m.  in  height  and  2.40-7  m.  in  diameter. 


Relative  specific  gravity 

Approximate  relative  fuel  value    ........' 

Coefficient  of  elasticity  in  kilograms  on  millimeters      '. 
Ultimate  transverse  strength  in  kilograms 
Ultimate  resistance  to  longitudinal  crushing  in  kilograms 
Resistance  to  indentation  to  1.27  mm.  in  kilograms 
(Sargent) 


0.4208 
42.02 
676. 
25s. 

1242. 


From  the   northern  borders  of  California  southward    through   the   coast 
ranges  to  near  the  southern  boundary  of  Monterey  County  (Sargent). 

2.  S.  gigaatea,  Decaisne 
Big  Trtt 

Transverse.  Summer  wood  very  thin,  of  2-6  tracheids,  the  transition  to 
the  spring  wood  usually  abrupt.  Spring  tracheids  large,  open,  thin- 
walled,  uniform,  squarish,  in  regular  row  s.  Resin  cells  not  vcrv  numer- 
ous, but  laige  ana  prominent,  scattering.  Medullary  rays  not  very 
prominent,  rather  numerous,  1  cell  wide;  distant  2-14',  rarely  ->c  rows 
of  tracheids.  •'  "^' 

Kadial.  y.a.y  cells  usually  .Mjmewhat  contracted  at  the  ends,  equal  to  6-8 
•spring  tracheids,  i  hiefly  resinous  throughout ;  the  upper  and  lower 
walls  thin  and  entire  or  distantly  pitted,  unequal  ;  the  terminal  walls 
thin,  straight  or  curved,  not  pitted  or  locally  thickened  ;  the  lateral 
walls  with  oval  and  commonly  narrowly  bordered  pits,  the  broadly 
oblong  oritice  equal  to  the  outer  limits  of  the  pit  nnd  chiefly  parallel 
to  the  cell  axis,  1^2,  or  more  rarely  3-4,  per  tracheid.  Bordered  pits 
in  one  or  two  row.s,  elliptical,  the  orifice  large,  elliptical.  Fits  on  the 
tangential  walls  of  the  summer  wood  prominent  and  frequent;  on 
the  tangential  walls  of  the  spring  wood  prominent  but  rare.  Resin 
cells  few,  about  20  ^  wide  and  140-325  n  long,  chiefly  about  250  u. 

Jangettiial.  Rays  chiefly  low  to  medium,  the  large  cells  broadly  oval  or 
round,  thin-walled. 


226 


ANATOMY  OF  THE  GYMNOSPERMS 


IH 


A  light,  soft  wood  remarkable  for  its  durability  in  the  soil.  The  tree  is  the 
lar;;est  produced  by  American  forests,  attaining  a  height  of  79-119  m. 
and  a  diameter  of  6-1 1  m. 

Relative  specific  gravity 0.2882 

Approximate  relative  fuel  value 28.67 

Coefficient  of  elasticity  in  kilograms  on  millimeters     .     .  451. 

Ultimate  transverse  strength  in  kilograms 196. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  6210. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  1091, 
(Sargent) 

Western  slopes  of  the  Sierra  Nevada  Mountains,  California,  from  Placer 
County  south  to  Deer  Creek  on  the  southern  borders  of  Tulare  County 
(Sargent). 

3.  *  *  S.  Langsdoifii  (Brongn),  Heer. 

Transi'trse.  Growth  rings  medium,  strongly  defined.  Tracheids  of  the 
spring  wood  squarish,  large,  S2x  52  ^  the  walls  14  fi  thick.  Summer 
wood  of  3-6  tracheids  in  thickness,  the  transition  from  the  spring 
wood  rather  abrupt.  Hesin  cells  rather  numerous  throughout  the 
growth  ring  and  scattering.  Resin  passages  usually  absent,  but  occu- 
sionally  appearing  in  a  rudimentary  form  on  the  outer  face  of  the 
summer  wood. 

Radial.  Medullary  rays  devoid  of  tracheids ;  the  parenchyma  cells  equal 
to  about  4  tracheids,  somewhat  constricted  at  the  ends ;  the  upper  and 
lower  walls  thin  and  entire ;  the  terminal  walls  not  pitted,  straight  or 
curved  ;  the  lateral  walls  with  no  recognizable  structural  details. 

Tangential.  Medullary  rays  i -seriate  or  rarely  2-seriate  in  part,  the  oval 
or  round  cells  about  31.5/11  broad. 

This  very  widely  distributed  and  well-known  Cretaceous  and  Tertiary  plant, 
which  is  chiefly  represented  by  foliage  and  fruit,  is  apparently  repre- 
sented also  by  the  woody  stem  in  the  Lignite  Tertiary  of  the  Porcupine 
Creek  and  Great  Valley  groups  in  Saskatchewan.  Reference  of  the 
wood  to  this  species  is,  however,  made  provisionally,  as  the  evidence  is 
not  such  as  to  warrant  an  absolute  decision.  The  occurrence  of  the 
genus  in  this  locality,  however,  indicates  that  it  at  one  time  occupied 
the  present  prairie  region  in  preglacial  times,  and  that  its  recession  to  its 
present  narrow  limits  probably  occurred  as  the  result  of  glacial  action. 

4.  •  •  S.  Burgessii,  Penh. 

Transverse.  Growth  rings  chiefly  narrow  but  variable,  the  rather  narrow- 
but  variable  summer  wood  dense,  the  transition  from  the  spring  wood 
abrupt.  Tracheids  of  the  spring  wood  large,  squarish,  and  thin-walled. 
Resin  canals  wholly  wanting.  Resin  cells  numerous  throughout  the 
growth  ring,  but  especially  on  the  outer  face  of  the  summer  wood : 
with  dark,  massive  resin.  Medullary  rays  chiefly  I  cell  wide,  occa- 
sionally broader  and  bearing  a  resin  canal  with  large  thyloses. 


SEQUOIA 


227 


Radial.  Bordered  pits  large,  in  1-2  rows.  Medullary  rays  often  with  a 
large  resin  passage  bearing  thyloses;  the  cells  all  of  one  kind;  the 
upper  and  lower  walls  thin  and  much  altered  by  decay ;  the  lateral 
walls  devoid  of  recognizable  markings. 

Tangentiai.  Ordinary  rays  i-  or  sometimes  2-seriate  in  part;  the  fusiform 
rays  with  large  resin  passages  containing  thyloses. 

An  exceedingly  well-characterized  species  from  the  Eocene  of  the  Porcu- 
pine Creek  and  Great  Valley  groups. 


5.  *  •  S.  magniflca,  Knowlton 

"Trunks  often  of  great  size,  6-10  feet  in  diameter,  30  feet  high  as  now 
preserved,  bark  when  present  5  or  6  inches  in  thickness ;  annual  rings 
very  distinct,  2-3  mm.  broad." 

"  Transverse.  In  this  section  the  structure  appears  beautifully  preserved. 
The  rings  are  rather  narrow,  being  only  2  or  3  mm.  broad,  or  often 
only  1  mm.  They  are  very  sharply  demarked,  even  to  the  naked  eye. 
Under  the  microscope  the  rings  are  found  to  consist  of  a  band  of 
thick-walled  cells  that  is  never  more  than  1 5  rows  of  cells  deep  and 
often  reduced  to  2  or  3  rows.  The  cells  composing  the  spring  and 
summer  wood  are  of  uniform  size  and  inclined  to  hexagonal  in  shape. 
Those  of  the  fall  wood  are,  of  course,  compressed. 

"  The  resin  cells  are  numerous  and  may  be  readily  distinguished 
by  the  dark  contents.  They  occur  mainly  in  the  spring  and  summer 
wood. 

"  The  medullary  rays  seen  in  this  section  are  long,  straight,  and 
separated  by  usually  about  3  rows  of  wood  cells." 

"Radial.  This  section  is  the  least  satisfactory  of  all.  The  wood  cells 
show  well  under  the  microscope,  but  their  markings  are  very  obscure. 
By  prolonged  search  it  is  made  out  that  the  pits  are  in  i  row,  or  some- 
times 2  parallel  rows.  They  are  small,  as  far  as  can  be  made  out, 
and  are  too  obscure  for  satisfactory  measurement. 

"  The  rays  are  composed  of  long,  unmarked  cells." 

"  Tangential.  This  section  is  very  satisfactory.  The  wood  cells  are  long 
and  unmarked.  The  resin  ducts  are  numerous,  but  scattered,  the 
cells  being  twice  or  three  times  as  long  as  wide.  In  many  ca.ses  they 
are  filled  with  or  contain  masses  of  dark  material,  rcpre.senting  the 
resin  now  turned  to  a  carbonaceous  mass. 

"The  medullary  rays  are  compo.sed  of  1,  or  in  some  cases  of  a 
partially  double,  series  of  2  to  about  25  superimpcsed  cells.  They 
are  large  and  quite  thick-walled.  The  average  number  of  cells  in 
each  ray  is  about  12"  (Knowlton). 

According  to  Professor  F.  H.  Knowlton,  this  species  can  hardly  be  dis- 
tinguished from  the  existing  S.  sempervirens,  of  which  he  considers  it 
to  be  the  ancestral  form. 

Tertiary  of  the  Yellowstone  National  Park,  at  Specimen  Ridge,  Fossil 
Forest  at  head  of  Crystal  Creek,  Fossil  Forest  on  Cache  Creek,  etc. 
(Knowlton). 


328 


ANATOMY  OF  THE  GYMNOSPERMS 


6.  *  •  S.  Pentaallowii,  JefiFtey 

"  Tranmerse.  Rings  of  growth  rather  narrow,  with  sharply  marked  but  thin 
summer  wood.  Rings  regular,  or  if  varying  in  thickness,  varying  uni- 
formly and  without  violent  transitions  except  as  the  result  of  injury. 
Resin  canals  present  in  both  the  vertical  and  horizontal  planes  appar- 
ently only  as  the  result  of  injury.  The  resin  canals  when  present 
surrounded  by  resin  cells,  containing  dark  brown  resin.  Resin  cells 
inconspicuous  and  confined  to  the  face  of  the  summer  wood,  except 
in  the  case  of  injury,  where  they  may  be  present  throughout  the  zone 
of  annual  growth.  Tracheids  of  the  spring  wood  very  large  and  with 
pits  on  the  radial  walls  only.  T.acheids  of  the  summer  wood  with 
tangential  pits." 

"  Radial.  Rays  without  tracheidal  cells,  but  with  distinctly  differentiated 
marginal  cells.  Lateral  pits  of  the  ray  cells  elliptical,  bordered,  larger 
in  the  marginal  cells.  Rows  of  pits  single  in  the  central  cells  of  the 
ray  and  2-3  seriate  in  the  marginal  cells.  Medullary  ray  cells  covering 
1-4  tracheids,  the  central  ones  resiniferous,  the  marginal  generally 
empty,  sometimes  containing  large  clinorhombic  crystals  inclosed  in 
cysts  derived  from  the  cell  walls.  Marginal  cells  with  undulating  free 
border,  deeper  than  central  cells.  End  walls  of  the  cells  of  the  medul- 
lary rays  very  strongly  pitted.  Longitudinal  walls  of  ray  cells  also 
pitted  and  rather  thick.  Rays  contain  resin  canals  in  the  case  of 
injury,  which  take  their  origin  from  similar  vertical  canals  running  in 
the  wood.  Resin  canals  of  the  rays  sometimes  ending  blindly  and 
sometimes  in  a  more  external  series  of  vertical  canals,  often  extending 
through  many  annual  rings,  varying  greatly  in  size  and  frequently 
occluded  by  thyloses.  Spring  tracheids  generally  with  2  rows  of  oppo- 
site pits,  which  often  alternate  in  the  ends." 

"  Tangential.  Rays  of  one  kind  only  in  uninjured  parts  of  the  wood.  Fusi- 
form rays  present  with  linear  rays  in  the  case  of  injury  and  varying 
greatly  in  size.  Fusiform  rays,  when  present,  generally  with  central 
resin  canal,  which  is  often  occluded  by  thyloses.  Linear  rays  varying 
greatly  in  depth.  No  pits  on  the  tangential  walls  of  the  spring  tra- 
cheids. Pits  on  the  tangential  walls  of  the  summer  tracheids  numer- 
ous, generally  not  in  rows  "  (Jeffrey). 

Material  but  slightly  silicified  and  showing  little  alteration  through  decay. 

From  a  waterwom  fragment  of  a  trunk  originally  6  feet  or  more  in 

diameter. 
Miocene(i'),  trom  Tunnel  No.  1,  Central  Pacific  Railway,  at  Blue  Gap, 

Sierra  Nevada  Mountains  (Jeffrey). 

10.  •  CUPRESSUS,  TouRN.    Plates  38  and  39 

Transverse.  Summer  wood  usually  very  thin,  often  barely  distinguishable, 
the  structure  of  the  growth  ring  open  throughout.  Resin  passages 
wholly  wanting.  Resin  cells  prominent,  rather  numerous  in  bands, 
scattering  or  even  apparently  wanting. 


CUPRESSUS 


fig 


Radial.  Kays  chiefly  without  tracheids.  Terminal  walls  of  the  ray  cells  thin 
and  entire,  very  commonly  cu— cd,  often  locally  thickened.  Tracheids 
wholly  without  spirals. 

Tangential.  Fusiform  rays  wholly  wanting.  Ray  cell.s  chiefly  broad,  oval,  or 
even  transversely  oval ;  the  rays  sometimes  2-seriate  in  part. 

Synopsis  of  Species 

A.  *  CHAMi€CYPARIS 

Existing  S/iecies 

I.  Pits  on  the  tangential  walls  of  the  summer  tracheids  flat, 
small,  obscure,  or  at  least  not  prominent 
Ray  cells  (tangential)  round  or  oval. 
Ray  tracheids  absent. 

Tracheids  more  or  less  conspicuously  rounded  throughout. 
Ray  cells  (radial)  straight,  sparingly  resinous. 

Pits  on  the  lateral  walls  of  the   ray  cells  2,  in  radial 
series,  or  in  the  marginal  cells  6,  per  tracheid. 
5.  C.  obtusa. 
Tracheids  distinctly  squarish,  large,  the  structure  open. 

Pits  on  the  lateral  walls  of  the  ray  cells  2-4,  rarely  8,  per 
tracheid. 

2.  C.  Lawsoniana. 

Pits  on  the  lateral  walls  of  the  ray  cells  2,  in  radial  series, 
or  6,  per  tracheid. 

3.  C.  pisifera. 
Ray  tracheids  present  in  the  low  rays. 

Tracheids  distinctly  squarish,  or  again  rounded  and  thick-walled, 
the  structure  variable,  either  open  or  somewhat  dense. 
Pits  on  the  lateral  walls  of  the  ray  cells  1-4  per  tracheid. 
Tracheids  (transverse)  commonly  in  very  irregular  rows. 

4.  C.  nootkatensis. 
Ray  <  ells  (tangential)  narrow,  oblong,  more  rarely  oval. 

Tracheids  distinctly  squarish,  in  regular  rows,  the  structure  open. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-2,  or  in  the  marginal 
cells  and  low  rays  upwards  of  C,  per  tracheid. 
I.  C.  thyoides. 

B.   CUPRESSUS 

Existing  Species 

2.  Pits  on  the  tangential  walls  of  the  summer  tracheids  chiefly 
large  and  open 
Ray  cells  (tangential)  round  or  oval,  more  rarely  transversely  oval. 


230 


ANATOMY  OF  THE  GYMNOSPERMS 


Tracheids  more  or  less  conspicuously  rounded  throughout. 

Ray  cells  (radial)  somewhat  contracted   at  the  ends,   strongly 
resinous. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-2,  rarely  4,  per 
tracheid. 

6.  C.  macrocarpa. 
Tracheids  barely  if  at  all  rounded. 

Ray  cells  (radial)  contracted  at  the  ends,  more  or  less  resinous. 
Pits  on  the  lateral  walls  of  the  ray  cells  1-2,  rarely  3,  per 
tracheid. 

8.  C.  Macnabiana. 
Ray  cells  (tangential)  chiefly  transversely  oval. 

Tracheids  more  or  less  rounded  throughout. 

Ray  cells  (radial)  somewhat  contracted  at  the  ends,  barely  resinous. 
Pits  on  the  lateral  walls  of  the  ray  cells  1-2,  more  rarely  4,  per 
tracheid. 

7.  C.  arizonica. 
Tracheids  squarish,  the  structure  open  throughout. 

Ray  cells  (radial)  strongly  fusiform,  generally  resinous. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-2  per  tracheid. 

9.  C.  Goveniana. 


C.  *  •   CUPRESSOXYLON  (Cupressinoxylon) 

Extinct  Species 

Tracheids  of  the  spring  wood  distinctly  rounded. 
Bordered  pits  obliterated  by  dtcay. 

Medullary  rays  (tangential)  1-3  .seriate,  the  round,  thin-walled 
cells  47  n  broad. 

10.  C.  cheyennense. 
Bordered  pits  in  i  row,  distant,  round. 

Pits  on  the  lateral  walls  of  the  ray  cells   1-2,  chiefly  2,  per 
tracheid. 

Rays  (tangential)  numerous,  the  variable  cells  chiefly  broad, 
oval,  or  round,      metimes  transversely  oval. 

1 1 .  C,  macrocarpoides. 

Bordered  pits  large,  in  1  row,  or  often  in  pairs,  and  in  larger  tracheids 
becoming  more  or  less  2-rowed. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-2  per  tracheid. 

Medullary  rays  (tangential)  i-seriate,  the  round  cells  19  n 
broad. 

12.  C.  comanchense. 


CUFB^'iSUS 


231 


Tracheids  of  the  spring  wood  squansh  hexagonal. 
Bordered  piis  round,  distant,  in  1  row. 

13.  C.  pulchellum. 

14.  C.  arkansanum. 

Bordertd  pits  large,  in  i  row,  often  i  .  pairs,  the  latter  sometimes  so 
approximated  as  to  make  the  pits  more  or  less  2-rowed. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-2,  in  vertical  series,  or 
in  marginal  cells  and  low  rays  4,  per  tracheid. 

15.  C.  Dawsoni. 

Pits  on  the  lateral  walls  of  the  ray  cells  obliterated. 

16.  C.  Wardi. 

Pits  on  the  lateral  walls  of  the  ray  cells  minute,  round. 

Medullary  rays  (tangential)  small,  the  cells  small,  oblong, 
1S-17X  10  (t,. 

17.  C.  columbianum. 
Bordered  pits  conspicuously  in  2  rows. 

Pits  on  the  lateral  walls  of  the  ray  cells  obliterated. 
Growth  rings  obscure. 

18.  C.  elongatum. 
Growth  rings  sharply  defined. 

Tracheids  of  the  earlier  spring  wood  very  large  and 
thin-walled. 

19.  C.  glasgowi. 
Bordered  pits  in  2,  or  sometimes  3,  rows. 

Pits  on  the  lateral  walls  of  the  ray  cells  with  large,  oval  pits 
1-3  per  tracheid. 

20.  C.  McGeei. 

Pits  on  the  lateral  walls  of  the  ray  cells  3  per  tracheid. 

21.  C.  Calli. 


A.  CHAM/ECYPARIS 

1.  *  C.  thyoides,  Linn. 

fVAitt  Cedar 

Trans7'erse.  Growth  rings  thin,  variable,  the  structure  open  throughout. 
The  summer  wood  chiefly  thin,  of  2-6  tracheids,  the  transition  to  the 
spring  wood  rather  abrupt,  or  sometimes  thicker  and  not  clearly  sepa- 
rable from  the  spring  wood.  Spring  tracheids  lar^e,  conspicuously 
squarish,  uniform,  in  regular  rows,  in  small  stems  and  branches  often 
much  elongated  radially,  the  walls  not  very  thin.  Resin  ceils  widely 
scattering  and  often  apparently  wanting ;  when  in  bands,  often  giving 
the  appearance  of  secondary  growth  rings,  chiefly  in  or  near  the  sum- 
mer wood.  Medullary  rays  not  very  prominent  or  resinous,  i  cell 
wide,  distant  2-12  tracheids. 


232  ANATOMY  OF  THE  GYMNOSPERMS 

Radial.  Ray  tracheids  chiefly  narrow,  very  unequal,  often  high,  sometimes 
present,  then  rather  abundant  and  composing  the  enti  ray  when  of 
1  or  2  cells  only,  usually  absent  from  the  higher  rays.  Medullary 
rays  contracted  at  the  ends;  the  upper  and  lower  walls  medium  to 
thick,  unequal,  frequently  pitted  or  again  entire  or  distantly  pitted ; 
the  terminal  walls  thin,  often  curved  and  locally  thickened ;  the  lateral 
walls  with  round  or  oval  pits,  the  orifice  lenticular,  1-2,  or  in  the 
marginal  cells  and  low  rays,  6,  per  tracheid.  Pits  on  the  tangential 
walls  of  the  summer  tracheids  very  small  and  often  obscure.  Bor- 
dered pits  round  or  elliptical  in  1  row,  or  in  radially  broad  tracheids 
in  2  rows.  Kesin  cells  not  numerous,  20-25  y,  wide,  150-175  u 
long. 

Tangential.    Rays  medium,  wholly  i-seriate  ;  the  cells  narrow,  oblong. 

Wood  very  light  and  soft,  but  very  durable  in  the  soil. 

Relative  specific  gravity 0.3322 

Approximate  relative  fuel  value 33.12' 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  404. 

Ultimate  transverse  strength  in  kilograms 194. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  4149. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms     .     .  1074. 
(Sargent) 

Cape  Breton  Island  and  near  Halifax  (Macoun) ;  southern  Maine,  south- 
ward along  the  coast  to  Florida,  thence  westward  along  the  Gulf  coast 
to  Pearl  River,  Mississippi  (Sargent). 

The  Pleistocene  deposits  of  the  Don  Valley,  Toronto.  Material  not  pet- 
rified, but  often  showing  the  effects  of  advanced  decay. 

2.  C.  Lawsonijuu,  A.  Murr. 

Port  Orford  Cedar.    Oregon  Cedar.     White  Cedar.    Lawson's  Cypress. 
Ginger  Pine 

Transverse.  Growth  rings  very  narrow,  variable,  the  structure  very  open 
throughout.  Summer  wood  very  thin,  of  1-5  tracheids,  sometimes 
double  and  then  upwards  of  14  tracheids,  the  transition  to  the  spring 
wood  gradual.  Spring  tracheids  very  large,  squarish-hexagonal,  thin- 
walled,  in  very  regular  rows,  uniform.  Resin  cells  prominent,  large, 
usually  widely  scattering  and  not  numerous,  or  again  numerous  within 
narrow  zones  in  the  summer  wood.  Medullary  rays  resinous,  rather 
prominent  and  numerous,  i  cell  wide,  distant  1-9  or  12  tracheids. 

Radial.  Ray  tracheids  wholly  wanting.  The  straight  or  somewhat  con- 
tracted ray  cells  rather  resinous,  equal  to  3-12  spring  tracheids;  the 
upper  and  lower  walls  variablj,  often  strongly  thickened  toward  the 
ends  of  the  cells,  not  obviously  pitted;  the  terminal  walls  thickish, 
chiefly  straight,  not  pitted  or  locally  thickened  ;  the  lateral  walls  with 
small  bordered  pits  with  a  narrow  orifice,  1-4,  or  more  rarely  upwards 
of  8,  per  tracheid  and  chiefly  in  vertical  rows.  Bordered  pits  in  1 
row,  sometimes  in  2  rows,  round.    Pits  on  the  tangential  walls  of  the 


CUPRESSUS  233 

summer  tracheids  small,  rarely  large,  not  numerous.    Resin  cells  not 
numerous,  20-25  M  wide,  150-200  /i  long,  chiefly  about  175  ^. 
Tangenlial.    Rays  medium,  wholly  i-scriate;  the  cells  broadly  oblong  or 
oval,  sometimes  round,  the  walls  thick. 

A  light,  hard,  and  strong  wood  which  is  very  durable  in  the  soil. 

Relative  specific  gravity 0.4621 

Approximate  relative  fuel  value 46.16 

Coefficient  of  elasticity  in  kilograms  on  millimeters     .     .  1217. 

Ultimate  transverse  strength  in  kilograms 370. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  7435. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  131 7 
(Sargent) 

Oregon,  not  more  than  thirty  miles  from  the  coast ;  valley  of  the  upper 
Sacramento  River,  California  (Sargent). 

3.  C.  pUifera,  Sieb.  et  Zucc. 
/af.  =  Saviara 

Trans-verse,  Growth  rings  narrow,  uniform ;  the  usually  dense  and  very 
narrow  summer  wood  of  3-5  tracheids,  the  transition  to  the  spring 
wood  somewhat  abrupt ;  the  spring  wood  open,  the  large,  squarish- 
hexagonal  f'acheids  in  very  regular  rows,  uniform,  rather  thin-walled. 
Resin  cells  few,  dark,  and  prominent,  zonate  in  the  summer  wood. 
Medullary  rays  not  prominent,  I  cell  wide,  narrow,  distant  2-17 
tracheids. 

Radial.  Rays  devoid  of  tracheids,  nonresinous,  the  cells  contracted  at 
the  ends,  equ?"  -.0  5-6  spring  tracheids ;  the  upper  and  lower  walls 
thin,  rather  u.  qual,  not  obviously  pitted;  the  terminal  walls  thin, 
chiefly  curved,  not  pitted  or  locally  thickened ;  the  lateral  walls  with 
oval,  bordered  pits,  chiefly  2  per  tracheid  in  radial  series,  or  in  the 
marginal  ceils  and  low  rays  smaller  and  upwards  of  6  per  tracheid. 
Bordered  pits  elliptical,  large,  rather  numerous  in  i  row  or  sometimes 
in  pairs.  Pits  on  the  tangential  walls  of  the  summer  tracheids  rather 
few,  small,  flat,  and  inconspicuous.  Resin  cells  few  in  the  summer 
wood,  12.5-20  /*  wide,  170-250  //  long. 

Tangential.  Rays  low  to  medium,  narrow,  nonresinous ;  the  cells  rather 
variable  from  oblong  to  oval  or  round,  chiefly  rather  oblong,  rarely 
if  ever  in  pairs. 

4.  C.  nootkatcnsis.  Lam. 

Yellmv  Cypress.    Sitka  Cypress 

Trans7>erse.  Growth  rings  unequal.  Summer  wood  very  thin,  of  2-6 
tracheids,  the  transition  to  the  spring  wood  gradual.  Spring  tracheids 
chiefly  large,  but  very  variable  and  often  in  irregular  rows,  squarish 
Resin  cells  prominent  and  ra'ier  numerous,  either  scattering  or  com- 
pressed into  narrow  bands  in  both  the  spring  and  summer  wood. 
Medullary  rays  resinous,  prominent,  i  cell  wide,  distant  about  2-17 
tracheids. 


it. 


234  ANATOMY  OF  THK  GYMXOSPERMS 

Raiiial.  Ray  trarlicids  chiefly  short  and  broad  :  chiefly  or  wholly  confined 
lo  rays  r  or  2  cells  hi);h,  then  constituting  the  en'ire  ray,  not  very 
numerous.  Kay  cells  somewhat  resinous,  more  o'  less  conspicuously 
contracted  at  the  ends,  equal  to  4-9  sprinj;  trachoids ;  the  upper  and 
lower  walls  thick  and  entire  or  distantly  pitted;  the  terminal  walls 
thin  and  locally  thickened  ;  the  lateral  walls  with  rather  small  pits 
with  a  lenticular  orifice  often  parallel  with  the  cell  axis,  1-4  per 
tracheid.  Bordered  pits  round  or  elliptical  in  I  row,  somewhat  distant ; 
the  round  orifice  often  very  variable,  much  enlarged,  eccentric, 
irregular  in  outline  or  even  wanting,  the  pits  then  presenting  a  vari- 
able aspect  which  at  once  ser%es  to  define  the  species.  Pits  on  the  tan- 
gential walls  of  the  summer  tracheids  few,  often  ob.scure.  Resin  cells 
few,  about  20  /i  wide  and  100-175  ^  long,  rarely  upwards  of  270  /*. 

Tatttreniial.  Rays  low,  narrow,  and  i -seriate,  sometimes  2-seriate  in  part; 
the  cells  narrowly  elliptical  or  broadly  oval,  sometimes  transversely 
oval  or  oblong,  much  enlarged. 

This  is  the  most  variable  .species  of  Cupressus,  and  it  is  chiefly  remarkable 
for  the  variable  character  of  the  summer  wood,  the  irregular  disposition 
of  the  tracheids  (transverse),  the  often  very  numerous  resin  cells,  and 
the  peculiarly  imperfect  bordered  pits  which  at  once  separate  it  from 
all  other  species.  It  may  show  deviation  from  the  normal  in  (i)  the 
absence  of  resin  cells ;  (2)  the  form  of  the  tracheids,  which  are  some- 
times round  with  thick  walls,  even  in  the  same  section,  thus  giving  rise 
to  (3)  a  variable  structure  of  the  wood  which  is  in  some  rings  rather 
dense  throughout. 

A  large  tree  of  great  economic  importance  with  a  height  of  30-38  m.  and 
a  diameter  of  1.20-1.80  m.    Wood  light,  hard,  and  very  durable. 

Relative  specific  gravity 0.4782 

Approximate  relative  fuel  valu^          47.66 

Coefficient  of  elasticity  in  kilogram.    .  n  millimeters     .     .  1029. 

Ultimate  transverse  strength  in  kilograms 342. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  7281. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  161 8. 
(Sargent) 

Interior  of  Vancouver  Lsland ;  British  Columbia,  near  the  coast,  where 
it  reaches  sea  level  in  the  northern  portion.s,  and  thence  to  Alaska 
(Macoun)  ;  southward  through  the  Cascade  Mountains  of  Washington 
and  Oregon,  where  it  is  seldom  found  below  an  elevation  of  5000  feet 
(Sargent). 

5.  C.  obtusa,  Sieb.  et  Zucc. 

Jap.  =  Hinoki 

Transverse.  Growth  rings  broad.  Summer  wood  chiefly  rather  thin,  some- 
times double,  rather  open  but  passing  very  gradually  into  the  broad 
spring  wood  from  which  it  is  not  clearly  separable.  Tracheids  of  the 
spring   wood   round-hexagonal,    thickish-walled,   not  very  large,  the 


v 


CUPRESSUS 


^35 


utructure  not  very  open.  Resin  cells  prominent,  dark,  not  very  large 
or  numerous,  rather  sratterinj,'  or  again  zonate  in  both  spring  and 
summer  woods.  Medullary  rays  not  prominent  or  numerou.s,  rather 
narrow  and  i  tell  wide,  distant  1-23  fracheids. 

Kadial.  Medullary  rays  devoid  of  tracheids,  sparingly  resinous,  the  cells 
straight  and  equal  to  5-10  spring  tracheids;  the  upper  and  lower 
wa  s  thickish,  sinuately  unequal,  not  obviously  pitted  ;  the  terminal 
walls  thin,  curved  or  straight,  not  pitted  or  locally  thickened;  the 
lateral  walls  with  oval,  bo^ered  pits,  chiefly  i,  or  in  the  marginal 
cells  2,  per  tracheid,  the  orifice  lenticular-oblong.  Bordered  pits 
round  or  elliptical,  rather  distant  in  1  row,  usually  less  than  one  half 
the  diameter  of  the  tracheid.  Pits  on  the  tangential  walls  of  the 
summer  tracheids  not  very  numerous,  small,  flat,  obscure.  Resin 
cells  few,  15-25  fi.  wide,  150-210  /t  long,  chiefly  about  150  /*. 

Tangential.  ays  medium,  narrow;  the  uniformly  oval,  nonresinous  cells 
rarely  if  ever  in  pairs. 

B.  CUPRESSUS 
6.  C.  macrocupa,  Gordon 

Monterty  Cyprus 

Trans-verse.  Growth  rings  usually  broad.  Summer  wood  very  thin,  of  6-8 
tracheids,  and  passing  gradually  into  the  spring  wood  from  which  it 
is  not  always  clearly  .separable.  Spring  wood  very  broad,  the  tra- 
cheids unifcrm,  rather  large,  rounded-hexagonal,  the  walls  rather 
thick.  Resin  cells  prominent  and  widely  scattering  or  somewl... 
zonate  in  the  summer  wood.  Medullary  rays  prominent,  resinous, 
broad.  1  cell  wide,  distant  2-12,  rarely  33,  tracheids. 

Kadial.  Rays  devoid  of  tracheids  and  resinous  throughout.  Cells  more  or 
less  contracted  at  the  ends,  equal  to  4-6  spring  tracheids ;  the  upper 
and  lower  walls  variable  and  not  obviously  pitted  ;  the  ter.T.inal  walls 
thin,  often  curved,  locally  thickened  ;  the  lateral  walls  with  rather 
large  bordered  pits  with  large,  lenticular,  or  oblong  orifices,  1-2,  or  in 
the  low  rays  4,  per  tracheid.  Bordered  pits  round  or  elliptical,  some- 
times in  pairs.  Pits  on  the  tangential  walls  of  the  summer  tracheids 
numerous,  large,  and  open.  Resin  cells  not  numerou.s,  20-25  M  wide, 
40-65  /bt  long,  chiefly  about  50  /i. 

Tangential.  Rays  medium,  sometimes  2-seriate  in  part,  the  cells  broadly 
often  transversely  oval,  thick-walled. 

This  species  is  usually  recognized  by  the  very  large,  bordered  pits  on  the 
tangential  walls  of  the  summer  tracheids.  In  transverse  section  the 
summer  wood  commonly  presents  somewhat  strong  variations  in  speci- 
mens from  different  individuals. 

Wood  heavy,  hard,  strong,  and  very  durable.  Trees  upward  of  21  m  in 
height  and  i  .80  m.  in  diameter. 


Relative  specific  gravity 
(Sargent) 

California  (Sargent). 


0.6261 


if 


a^  ANATOMY  OF  THE  (lYMNOSPERMS 

7.  C.  arlMnk*,  Cireene 

I'yfrtss 

Transvtrst.  Growth  rings  medium,  rather  uniform.  Summer  wood  very 
thin,  upwards  of  6  tracheir*  and  passing  very  gradually  into  the 
spring  wood.  The  very  broad  spring  wood  somewliat  open,  the  very 
variable  tracheids  chiefly  squarish-hexagonal,  the  walls  not  thin. 
Kesin  cells  numerous  and  prominent,  narrowly  zonate  in  both  the 
spring  and  summer  woods,  sometimes  in  groups  of  larger  and  thicker- 
walled  cells,  showing  a  tendency  to  the  formation  of  resin  canal.s. 
Medullary  ray.s  rather  prominent,  somewhat  resinous,  rather  numerouii 
and  broad,  i  cell  wide,  distant  2-10  tracheids. 

Radial.  Rays  devoid  of  tracheids  and  sparingly  resinous,  the  cells  con- 
spicuously contracted  at  the  ends,  equal  to  about  6-9  spring  tracheid.s ; 
the  terminal  walls  chiefly  straight,  sparingly  and  locally  thickened  ;  the 
upper  and  lower  walls  medium  to  thick,  not  obviously  pitted  ;  the  lat- 
eral walls  with  round  or  oval  pits  1-2,  or  in  the  marginal  cells  4,  per 
tracheid.  Bordered  pits  round  or  elliptical,  rather  numerous,  in  1  row. 
Pits  on  the  tangential  walls  of  the  summer  tracheids  rather  numer- 
ous and  large,  open.  Kesin  cells  not  numerous,  1 5-20  ^  wide,  1 20- 
250  ^lon§,  chiefly  about  200/1;  sometimes  in  multiple  .sei'es  of  much 
broader,  very  variable,  often  isodiametric  and  thick-walled  cells,  show- 
ing a  strong  tendency  to  the  formation  of  resin  canals. 

Tangential.  Kays  medium,  the  cells  broad,  more  or  less  resinous,  trans- 
versely oval,  or  in  the  low  rays  vertically  oval. 


Wood  soft,  light,  and  coarse  grained. 


Kelative  specific  gravity 
(Sargent) 


0.4843 


San  Francisco  Mountains  of  New  Mexico  and  Arizona,  where  the  tree 
forms  extensive  forests  on  the  northern  slopes  of  the  mountains  at  eleva- 
tions of  5000-8000  feet ;  Santa  Catalina  and  Santa  Kita  mountain.s  of 
Arizona ;  on  the  Sierra  Madre  and  Guadeloupe  Islan  1  Mexico  (Sargent). 


8.  C.  Macnabiana,  A.  Murr. 
Cypress 

Transverse.  Growth  rings  medium,  uniform.  Summer  wood  very  thin,  of 
about  3-5  tracheids,  open,  the  transition  to  the  spring  wood  gradual. 
The  L.road  spring  wood  rather  open,  the  tracheids  conspicuously  he,\- 
agonal,  rather  uniform,  the  walls  medium.  Resin  cells  prominent,  not 
numerous,  widely  scattering  throughout  the  growth  ring.  Medullary 
rays  prominent,  somewhat  resinous,  i  cell  wide,  distant  i-io,  rarely 
14,  tracheids. 

Jiadial.  Kays  wholly  devoid  of  tracheids,  more  or  less  resinous  throughout, 
im  idual  cells  often  strongly  so.  The  cells  somewhat  contracted  at 
thi,  inds,  equal  to  4-5  spring  tracheids ;  the  upper  and  lower  walls 
medium,  unequal,  entire,  or  sparingly  pitted  ;  the  terminal  walls  thin  and 


CUPRESSUS  237 

chiefly  straiKht,  locally  thickened  ;  the  lateral  walls  with  oval  or  round 
hr  iered  pits,  orifice  lenticular,  1-2,  or  in  the  marginal  cells  rarely  3, 
per  tracheid.  Bordered  pits  rather  numerous  in  1  row,  elliptical,  the 
orifice  large.  Pits  on  the  tangential  walls  of  the  summer  trachuds 
rather  numerous  and  large,  the  orifice  bell-shaped,  not  very  open. 
Resin  cells  not  numerous,  12.5-25  or  sometimes  35  fi  broad,  210- 
310  n  long,  chiefly  about  250  fi. 
TanKtHtial.  Rays  low,  the  cells  broad,  oval,  or  round,  often  resinous. 

A  small  tree  of  the  mountains  of  Lake  County,  California  (Sargent). 

9.  C.  QoreniMU,  Gordon 
Cyprtss 

Transverse.  Growth  rings  variable.  Summer  wood  very  thin,  of  2-6 
tracheids;  the  transition  to  the  spring  wood  gradual.  Spring  wood 
very  open,  the  tracheids  large  and  squarish,  in  regular  rows,  rather 
uniform  and  thin-walled.  Resin  cells  abundant  and  prominent,  in 
narrow  but  well-defined  zones,  sometimes  forming  rather  extended 
radial  .serie-s,  1  to  3  cells  wide,  of  broader  and  thicker-walled  cells. 
Medullary  rays  rather  numerous  but  not  very  resinous  or  prominent, 
I  cell  wide,  distant  2-8,  rarely  15,  tracheids. 

Radial.  Rays  devoid  of  tracheids,  more  or  less  resinous.  Ray  cells  con- 
spicuously narrower  at  the  ends,  equal  to  3-8  .sprinj;  tracheids,  becom- 
ing shorter  in  the  summer  wood  ;  the  upper  and  lower  walls  medium, 
entire  or  distanUy  pitted  ;  the  terminal  walls  thin,  often  locally  thick- 
ened :  the  lateral  walls  with  round  or  oval  pits  having  large,  round  or 
oval  openings,  1-2,  or  in  the  marginal  cells  4,  per  tracheid.  Bordered 
pits  elliptical,  sometimes  round  in  I  row,  becoming  much  more  dis- 
tant and  smaller  toward  the  summer  wood.  Fits  on  the  tangential 
walls  of  the  summer  tracheids  rather  numerous,  prominent,  chieHy 
large  and  open.  Resin  cells  rather  abundant,  10-20 ;x  wide,  185-375  /x 
long,  chiefly  about  225  fi;  sometimes  in  radially  wide,  multiple  .series 
of  broad  and  short,  thick-walled  cells. 

Tanf^ential.  Rays  low  and  broad,  sometimes  2-seriate  in  part;  the  cells 
thick-walled,  chiefly  transversely  oval. 

This  species  is  largely  distinguished  by  the  smaller  pits  on  the  lateral  walls 
of  the  strongly  contracted  ray  cells,  and  by  the  transversely  oval  ray  cells 
as  shown  in  tangential  section. 

A  small  tree  ftirnishing  a  light,  soft  wood. 

Relative  specific  gravity 0.4689 

Approximate  relative  fuel  value 46.68 

Coefficient  of  elasticity  in  kilograms  on  millimeters       .     .  499. 

Ultimate  transverse  strength  in  kilograms       230. 

Ultimate  resistance  to  longitudinal  crashing  in  kilograms  5742. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms       .     .  2852. 
(Sargent) 

Humboldt  County.  California,  south  along  the  coast,  and  through  the  coast 
ranges  into  southern  California  (Sargent). 


238 


ANATOMY  OF  THE  OYMNOSPERMS 


I 

5 
I   I 


C.  *«  CUPRESSOXYLON  (CuprtMinoxytoo) 

ExIintI  Sftcits  Only 

10.  •  *  C.  dwytnaeiiM,  Penh. 

Tra$uvtne.  W  ,  leid*  in  regular,  radial  rows,  rather  uniform,  roundish, 
about  6:--  ^  broad;  the  walls  15.5  ^  thiclc.  Resin  passai{e»  and 
aper  '  i  ells  wanting.  Growth  rings  apparent,  very  broad;  ma 
nditi  .xtent  of  20  mm.,  3  growth  rings  of  an  equal  thicknesx  of 
ic  ni  i>  "c  F)  esented.  The  tummer  wood  conspicuous,  ahmut  3-4 
cellx  .<  ,  t'  tracheids  about  29  x  38  ^  broad,  the  tani^ential  wall.s 
at'.      I  ,.r  /I .  ick. 

Radial.  I'tay  cr .  s  ;»'  of  one  kind,  straight ;  the  upper  ■■■  A  lower  walls  thin 
anu  to»  n  '  the  terminal  walls  thin  and  not  pitted,  strait'^t  or 
Cttrvi'J  ir  !  1^  ml  wftlls  showing  no  structure  which  has  been  oblit 
cnte<t  !  V  a>.'  .w  ,  tracheids  long. 

TaMgeit  it.  K.iys  %i\x,  •■.•■i.<»,  .nedium,  1-3  seriate;  tht  cells,  round,  thin- 
w  i>,i  ',    7  (II  |jn.vi. 

Material  h  icificd.    './(.' Imens  represented  by  small  portions  of  stem. 
From  the  C  .eyenni.  Frnuition  (Comanche  Cretaceous),  east  of  Stokes  Hill, 
Kiowa  I  nd  tiaker  Coun'y  line,  Kansas  (Frosser). 

11.  *  *  C.  nucrocarpoldet,  Penh. 

Transverse.  (Jrowth  rings  rather  broad.  Tracheids  of  the  spring  wood 
round  but  thin-walled  through  the  obvious  effects  of  decay ;  ratlirr 
uniform  in  regular  rows,  and  pas.sing  gradually  into  the  rather  thin  but 
conspicuous  summer  wood.  Resin  pa-ssages  wholly  wanting.  Resin 
cells  not  recognizable.  Medullary  rays  prominent,  often  2  cells  wide, 
distant  1-6  rows  uf  tracheids. 

Radial.  Medullary  rays  wholly  devoid  of  tracheids.  Ray  cells  more  or  kss 
conspicuously  contracted  at  the  ends,  equal  to  about  6  spring  tratlu  ids; 
the  upper  and  lower  walls  rather  thin  and  sparingly  pitted  ;  the  tt-rmi- 
nal  walls  chiefly  straight,  sometimes  curved,  not  pitted  or  obviously 
thickened  locally  ;  the  lateral  walls  with  oval  or  round  i^its,  1-2,  chittiy 
2,  per  tracheid.  Bordered  pits  in  i  row,  chiefly  distant,  round.  1  s 
on  the  tangential  walls  of  the  summer  wood  not  recognizable.  Ri-  m 
cells  present  on  the  outer  face  of  the  summer  wood  (?),  30  «  wide  .  id 
12s  /tlong. 

Tangential.  Fusiform  rays  wholly  wanting.  Ordinary  rays  numerous,  low 
to  high,  often  more  or  less  2-seriate,  rarely  3-seriate  in  part ;  the  n  Hs 
variable,  chiefly  broad,  oval  or  round,  or  sometimes  transversely  o\  .i 
Resin  cells  rather  numerous,  usually  very  long,  the  resin  scatteriiig  in 
small  globules. 

Material  silicitied. 

Cretaceous  near  Medicine  Hat,  Alberta;   Tertiary  of  Kettle  Kiver,  near 
Midway,  British  Columbia. 


CLFRFSSOXYI.ON 


839 


13.  *  *  C.  conMncbtnM,  i'enh. 

TraHSVtrs*.  Tracheids  in  reRular.  radial  rows,  rounded,  very  uniform,  44* 
44  M  broad,  the  w..l U  1 2.5  ^  ,h,ck.  Growth  rinR.  prominent.  alHiuMo 
in  a  radul  extent  0/22  mm. ;  the  summer  wood  thin,  compoHed  of  2-4 
rows  of  iracheid*.  the  latter  al)out  22  ^  wide,  the  walls  i7.5  u  thiclT 
Kesm  pa»»aKfH  and  resin  cells  wholly  wantinK.  Worm  burrows  are  fre-' 
quent  and  show  copious,  exudation  of  resin,  which  W^  often  preserved 
the  adjacent  structure  from  decay.  F":«-rvco 

AW/ii/.  Ray  cells  of  one  kind  only,  straight;  the  upper  and  lov^^r  walls 
thin  and  not  pitted ;  the  terminal  walls  thin,  not  pitted.  chicHv  curved '• 
the  lateral  walls  with  oval,  bordered  pits,  about  1-2  per  tracheid,  the 
oblong  or  broadly  lenticular  orifice  nearly  as  long  as  the  pit ;  the  ceils 
equal  to  alwut  4  tracheids.  Bordered  pits  round,  lar-c,  10  abroad  • 
in  I  or  sometimes  2  rows,  the  orifice  round.  ' 

raii,:ential.  Rays  1 -seriate,  the  cells  thin-walled,  round,  19  ^  broad. 

Material  silicified.   SpecimcrLS  r-pre.sented  by  small  fragments  of  a  stem. 
Comanche  Cretaceous  (?)  norttrwe.st  of  Ashland,  Clark   County,  Kan.sa» 
(Pro>ser). 

18.  *•  C.  pulch«UttBi,  Knuwiton 

"  Tmnsverse.  The  pith  is  well  pre.se-ved  and  onsi.sts,  when  vieuccl  under 
the  microscopi  of  numerous  large,  rather  hick-walled  cells  with  an 
ellnic  or  nearly  circular  outline.  The  i.  ger  cell.s,  which  have  a 
diameter  of  .05-.08  mm  ,  occupy  the  censer,  from  which  they  de 
cr«-av  in  size  and  pa.ss  more  or  less  gradually  into  the  mtclullarv 
ray-  The  rays  are  very  numerous  and  pa.ss  in  nearly  a  straight  line  to 
the  circumference.  No  trace  of  bark  remains.  The  tracheids  are 
arranged  with  great  regularity  in  radial  rows,  and  are  remarkable  for 
their  .small  size,  particularly  where  they  are  in  contact  with  the  |)ith 
As  the  medullary  rays  diverge,  new  layers  of  tra  lieids  are  ntercalated 
to  hll  up  the  .space.  The  line  of  demarcation  l,ctw..i  he  annual 
layers  is  generally  well  defined,  the  fall  «  .fl  consisting  ..;  8  com- 
pressed cells  in  ea<  h  radi;il  row.  The  spn  .g  wood  coiisi.sis  ,.f  much 
larger  cells,  which  have  a  diameter  of  .025-035  v.  m.  i  hese  ci  are 
mor.  nearly  hexagonal  than  the  others,  and,  dec  a.sing  gradi.  v  in 
size,  pa.ss  into  the  next  ring  of  fall  wood. 

"  Raihal.  In  this  section  the  tracheids  an  seen  to  be  iont  nd  ]»  ided 
With  a  single  longi'  dinal  ro«  of  border,  d  pits,  Ah  it'  h  can.,  rage 
outer  diameter  of  .uiy-.o^i  inm.  The  inner  cir.  '-  ihc  pit-  is  .ailur 
small,  with  a  diameter  of  .005-.006  11  n.  Tl 
cut  up  into  comparatively  short  cells,  e.u  h  o 
of  five  or  Nix  of  the  tracheids;  marViin-  si 
the  walls  of  the  rays,  but  the  real  state  of  lii 
(Jetrifying  materia!,  which  b.as  evidently  'W. 
original  structure  The  resin  tiucts  (tt-lis,  r> 
sist  of  a  chain  of  short,  regular  cells  hid  ..n 
the  end-      The  individual    cells  ai        ,8- 


usually  nlled  with  minute  globules  of  .Market  mailer 


medullar     rays    are 
'  '  \  L-riJig   the  spa  e 
'   to   i>e  absent   from 
lay  !»!  masked  by  the 
A  hat    lisorganized  the 
lumerous.      These  con- 
slightly  constricted  at 
iini    in  length,  and  are 


fl 


340 


ANATOMY  OF  THE  GYMNOSPERMS 


"  Tangential.  The  medullary  rays  are  very  abundant.  They  are  always 
simple  and  consist  of  a  single  layer,  which  ranges  from  i  to  1 5  cells 
in  height,  the  average  being  about  7  or  8.  The  tracheids  do  not  show 
bordered  pits  on  the  tangential  walls,  a  fact  of  considerable  impor- 
tance" (Knowlton). 

Remains  silicified. 

From  the  Potomac  Formation  at  Spring  Hill,  Virginia  (Knowlton). 


14.  *  *  C.  arkanaanum,  Knowlton 

"  Transverse.  The  annual  ring  is  either  entirely  absent  or  so  obscured  by 
the  mass  of  crushed  cells  as  to  be  indistinguishable.  In  a  single, 
exceptionally  well-preserved  spot  the  tracheids  are  seen  to  be  arranged 
in  nearly  uniform  radial  row.s,  there  being  generally  about  3  or  4  rows 
between  2  medullary  rays.  The  rays  are  abundant  and  consist  of  a 
single  cell. 

"  Radial.  The  tracheids  are  rather  thick-walled  and  provided  with  a  single 
row  of  pits.  The  pits  are  rather  distant,  the  outer  circle  having  a  diam- 
eter of  .01 1 -.01 45  mm.,  and  the  inner  a  diameter  of  .0028-.0048  mm. 
The  medullary  rays  are  abundant,  and  usually  only  a  single  series  thick, 
although  a  few  may  be  found  with  2  .series  of  cells  in  the  center. 

"  Tangential.  The  material  is  not  sufficiently  well  preserved  to  determine 
the  medullary  rays  satisfactorily"  (Knowlton). 

Remains  silicified. 

From  the  Tertiary  deposits  (Orange  sands)  of  Poinsett  County,  Arkansas 
(Knowlton). 

15.  •  •  C.  Dawaoni,  Penh. 

Transverse.  Growth  rings  variable,  chiefly  medium  to  broad.  Tracheids 
of  the  spring  wood  large,  thin-walled,  conspicuously  squarish,  and 
passing  gradually  into  the  u-sually  thin  but  rather  prominent  summer 
wood,  which  may  occasionally  become  thicker  and  without  definite 
internal  demarcation.  Resin  passages  wholly  wanting.  Resin  cells 
numerous  and  conspicuous  throughout  the  growth  ring,  often  in  more 
or  less  prominent,  tangential  row.  Medullary  rays  prominent,  resin- 
ous, I  cell  wide  but  rather  broad,  distant  2-9  rows  of  tracheids. 

Radial.  Medullary  rays  devoid  of  tracheids.  Ray  cells  resinous,  contracted 
at  the  ends,  equal  to  5-6  spring  tracheids ;  the  upper  and  lower  walls 
thin  and  sparingly  pitted ;  the  terminal  walls  straight,  or  sometimes 
strongly  curved,  not  pitted  or  locally  thickened  ;  the  lateral  walls 
with  round  or  oval  pits,  1-2  per  tracheid  in  vertical  series,  or  in 
marginal  cells  and  low  rays,  or  over  very  broad  tracheids,  becoming  4 
per  tracheid.  Bordered  pits  large,  in  i  row,  often  more  or  less  in  pairs, 
and  so,  over  broad  tracheids,  becoming  more  or  less  2-rowed.  Resin 
cells  numerous,  35-40  fi  wide,  200  /i  long. 

Tangential.  Medullary  rays  of  one  kind  only  and  i -seriate;  the  cells 
rarely  in  pairs,  large,  thin-walled,  oval  or  oblong,  usually  brc-id,  ant! 
often  becoming  transversely  oval  in  all  except  the  terminal  cells. 
Resin  cells  as  in  the  radial  section. 


CUPRESSOXYLON 


241 


Material  silicified. 

Eocene  of  the  Great  Valley  and  Porcupine  Creek  groups,  the  province  of 

Saskatchewan;   Cretaceous  of  the  south  Saskatchewan  near  Medicine 

Hat,  AlberU. 

16.  C.  Watdi,  Knowlton 

"  Transverse.  Material  too  fragmentary  and  too  poorly  preserved  to  show 
the  annual  rings  to  the  naked  eye,  but  they  are  apparent  under  the 
microscope.  The  fall  wood  consists  of  3-6  or  3-8  compressed  cells 
m  radial  rows.  The  spring  wood  contains  some  very  large  cells,  with 
a  diameter  in  some  instances  of  .062  mm.  The  number  of  cells  in 
each  row  of  tracheids  varies  according  to  the  width  of  the  annual 
ring,  there  being  frequently  as  much  as  100.  Large  intercellular 
spaces  occur,  especially  where  additional  rows  of  tracheids  have  been 
introduced. 

"^tfrtVfl/.  Tracheids  provided  in  i  row,  or,  in  some  instances,  with  2  lon- 
gitudinal rows  of  bordered  pits.  They  occupy  the  center  of  the  cell, 
and  are  in  close  relations,  almost  touching  in  some  cases  The  larger 
have  a  diameter  of  .02  mm.,  and  the  smaller  a  diameter  of  .015  mm 
The  medullary  rays  consist  of  typical  parenchymatous  tissue.  The 
individual  cells  are  short,  covering  a  width  of  4-8  tracheids.  Pits  on 
the  lateral  walls  of  the  rays  not  observable,  possibly  due  to  the  poor 
state  of  preservation.  The  resin  ducts  (cells)  are  not  very  numerous. 
They  are  of  nearly  the  same  size  and  shape  as  the  tracheids,  and  in 
fact  look  very  much  like  tracheids  with  transverse  partitions  Thev 
are  almost  always  empty. 

"  Tangenlial.  The  tracheids  are  not  provided  with  pits  on  the  tangential 
walls,  Of  at  least  none  have  been  detected.  The  medullary  rays  in 
many  cases  are  2  <rl!s  broad,  and,  as  indicated,  1-35  cells  high 
The  individual  celLs  of  the  rays  have  a  diameter  of  .017- oT  mm" 
(Knowlton). 

Material  silicified.    Specimens  represented  b)  small  fragments  only. 
From  the  Potomac  Formation  on  the  line  of  the  Baltimore  and  Ohio  Rail- 
road, between  Montello  and  Rives  Station,  D.C.  (Knowlton). 

17.  C.  oolumbianiun,  Knowlton 

"  Transverse.  The  annual  ring  is  very  indistinct,  although  not  entirely 
absent,  as  slight  traces  of  it  are  to  be  observed  among  a  mass  of 
crushed  cells.  Tracheids  in  very  regular,  radial  rows,  and  remarkable 
for  their  nearly  uniform  size  and  thick  walls.  The  larger  cells  are 
about  .OS  mm.  in  diameter,  the  smaller  .03 -.04  mm.  in  diameter. 
The  medullary  rays  are  not  abundant  and  appear  very  narrow. 

"Radial.  The  tracheids  are  thick-walled  and  covered  with  i,  or  rarely 
2,  rows  of  bordered  pits,  which  are  rather  small.  The  larger  pits 
have  a  diameter  of  .015  mm.  and  the  smaller  a  diameter  of  only 
.01  mm.  The  rays  consist  of  long  cells,  in  some  cases  provided  with 
minute,  round  punctations.  The  resin  ducts  (cells)  are  numerous. 
In  most  cases  they  consist  of  a  regular  chain  of  short,  constricted 
cells.    In  some  cases  they  contain  small  globules  of  resinous  matter. 


!    ; 


^i.. 


242 


ANATOMY  OF  THE  GYMNOSPERMS 


(^^^1 

^^■;- 

^^M' 

Hi 

;  i'l^H 

^1 

^^K§^ 

H 

Bpl' 

'  ^^1 

■^Ki ' 

^^H 

^^g! 

flH| 

HfHi 

"  TangtHtial.  The  medullary  rays  have  very  small  cells  which  have  a 
long  diameter  of  .01S-.017  mm.  and  a  short  diameter  of  only  .01  mm. 
The  walls  of  the  tracheids  are  so  thick  and  the  rays  so  small  that 
the  walls  between  which  they  appear  are  but  slightly  bulged.  The 
tracheids  do  not  exhibit  pits  on  the  tangential  walls"  (Knowlton). 

Remains  silicified.    The  specimen  is  represented  by  numerous  fragments 

of  stem,  upwards  of  25  cm.  in  length. 
The    Potomac  Formation  of  Dutch  Gap  and  Nebasco  Creek,  Virginia 

(Knowlton). 

18.  C.  dongatam,  Knowlton 

"  Transrerse.  Annual  rings  apparent  to  the  naked  eye,  but  faint,  J -6 mm. 
broad.  The  layer  of  the  fall  wood  is  narrow,  consisting  of  only  6-10 
rows  of  flattened  and  thick-walled  rclls.  The  cells  of  the  spring  and 
summer  wood  are  much  larger  and  rectangular  in  outline.  Their 
radial  diameter  is  as  great  as  .105  mm.  in  some  cases,  while  the  tan- 
gential 'iameter  is  only  .035-.04  mm.  The  average  size  is  about 
.07  mm.  in  long,  and  .03-.0S  mm.  in  short,  diameter.  The  medullary 
rays  are  observed  to  be  numerous.  The  largest  cells  are  in  contact 
with  the  med"llary  rays. 

"  Radial.  The  wood  cells  or  tracheids  appear  broad  and  thick-walled,  and 
to  be  provided  with  2  rows  of  very  large  pits  which  nearly  touch  in 
the  center,  and  are  in  contact  with  the  walls  on  the  outside.  The 
diameter  of  the  outer  circle  is  .02  mm.,  that  of  the  inner  circie 
.004-.006  mm.  They  are  rarely  in  a  single  row  when  they  occupy 
the  center  of  the  cell.  The  resin  ducts  consist  of  a  chain  of  short 
cells,  the  contents  of  which  are  not  preserved.  Medullary  rays  abun- 
dant;  individual  cells  long,  covering  the  width  of  6  or  8  tracheids; 
thin-walled.  They  seem  not  to  have  been  provided  with  pits  or 
markings. 

"  Tangential.  Medullary  rays  in  a  single  series,  and  rarely  of  1-44  super- 
im  josed  cells.  It  is  not  common  to  find  rays  with  less  than  5  cells  or 
more  than  30,  the  average  being  about  10-25.  No  pits  on  the  wails 
of  the  tracheids"  (Knowlton). 

Remains  silicified.    Specimen  represented  by  a  log  about  30  feet  long  in 

a  clay  soil. 
From  the  Laramie  of  Tiger  Butte.s,  Dawson  County,  Montana  (Knowlton). 

19.  C.  glasgowi,  Knowlton 

"  Trans7>erse.  Annual  rings  very  ..harply  marked,  3-4J  mm.  broad.  Under 
the  microscope  the  cells  aie  shown  to  be  arranged  in  strict  radial 
rows,  and  in  the  b?ind  of  summer  wood  consist  of  a  layer  of 
18-30  cells  more  or  less  completely  lignified.  In  the  outer  layers 
of  this  lignified  band  of  fall  wood  the  lumen  of  the  cells  is  reduced 
to  a  minimum.  The  lumen  is  in  the  form  of  an  ellip.se,  of  which  the 
long  diameter  is  less  than  .01  mm.  and  the  short  diameter  .ilxjut 
.005  mm.  In  the  immediately  following  layer  of  spring  wood  ilie 
cells  are  very  large  and  thin-walled,  measuring  .08  mm.  in  long,  and 


CUPRESSf>XYLON 


2-J3 


.05  mm.  in  short,  diameter.  In  the  .summer  wood  the  cell.s  ijecome 
smaler  and  more  nearly  hexagonal  in  outline,  and  pass  abruptly  into 
the  band  of  fall  wood.  ' 

"Radial.  In  this  section,  as  in  the  transverse,  the  demarcation  between 
fall  and  spring  wood  is  very  clearly  marked.  The  walls  of  the  cells 
in  the  spnng  and  summer  wood  are  the  only  ones  provided  with  bor- 
dered pits,  and  in  these  they  seem  not  to  have  been  very  abundant, 
or  at  least  are  not  preserved  in  a  manner  capable  of  demonstration 
These  pits  are  usually  arranged  in  2  parallel  rows,  although  in  some 
cases  there  is  but  i  row,  when  it  occupies  the  center  of  the  cell.  The 
pits  are  large,  and  when  in  2  rows  take  up  nearly  the  entire  width 
of  the  cell.  The  diameter  of  the  outer  circle  is  in  extreme  cases 
fully  .025  mm.,  the  average  being  about  .02  mm. ;  the  diameter  of  the 
mner  circle  is  only  .0025-.004  mm.  The  medullary  rays  are  observed 
to  be  numerous,  with  the  individual  cells  very  long.  The  latter  are 
not,  however,  very  high,  and  they  are  thin-walled.  The  pits  on  the 
lateral  walls  are  not  recognizable.  The  resin  ducts  are  moderately 
numerou.s.  They  are  composed  of  a  chain  of  .short,  thin-walled  cells 
.IS-.2S  mm.  in  length,  and  are  partially  filled  with  a  dark  mass  repre- 
senting the  resin. 

"  Tangential.  In  this  section  the  medullary  rays  are  observed  to  be  com- 
posed of  a  single  series  of  cells  which  ranges  from  3  to  30  in  number 
It  is  rare,  however,  to  find  them  with  as  few  as  3  or  as  many  as  30 
cells,  the  average  number  being  from  8  to  15.  Bordered  pits  have 
not  been  observed  in  this  section  "  (Knowlton). 

Material  silicified. 

Cretaceous  (?)  of  Emmet  County,  Iowa  (Knowlton). 

20.  C.  McGeei,  Knowlton 

"  Transverse.  The  tracheids  are  arranged  in  strictly  radial  rows.  The 
annual  ring  is  broad,  consisting  in  some  cases  of  as  many  as  50  or 
60  of  the  larger,  and  10-16  of  the  smaller,  thick-walled  cells.  The 
larger  cells  are  mostly  quadrangular  in  outline  and  have  a  diameter  in 
some  instances  of  .08  mm.,  the  average  being  about  .068  mm.  The 
cells  of  the  fall  wood  have  very  thick  walls  and  are  much  flattened. 
Intercellular  spaces  are  frequently  observed,  particularly  where  ad- 
ditional rows  of  tracheids  have  been  intercalated.  The  medullary  rays 
are  moderately  numerous. 

"Radial.  The  large  size  of  the  tracheids  is  verj-  clearly  shown,  and  they 
make  up  the  bulk  of  the  section.  The  tracheids  of  the  fall  wood  are, 
of  course,  much  smaller,  and  are  covered  with  but  a  single  row  of 
pits.  The  bordered  pits  are  very  close  together  on  the  summer  wood, 
and  are  always  in  2,  and  in  some  exceptionally  large  celLs,  in  3  rows. 
They  are  also  very  large,  the  out.r  circle  having  a  diameter  of  .02- 
.025  mm.,  and  the  inner  of  .00S-.008  mm.  The  walls  of  the  medul- 
lary rays  are  marked  by  large,  oval  jwres,  from  1  to  3  of  which 
occupy  the  width  of  a  .single  wood  cell.  The  resin  ducts  consist  of 
a  chain  of  short,  small,  thin-walled  cells,  which  now  contain  a  .small 
quantity  of  granular  matter,  representing  probably  drops  of  resin. 


244 


ANATOMY  OF  THE  GYMNOSPERMS 


The  individual  cells  have  a  length  of  .12-.2S  mm.,  and  a  diameter  of 
about  .05  mm.,  slightly  less,  it  will  be  observed,  than  the  tracheids 
among  which  they  run. 
"  Tanf^ential.  The  medullary  rays  are  always  simple ;  that  is,  they  consist 
of  but  a  single  row  of  cells,  which  varies  from  2  to  49  cells  in  height. 
The  tracheids  are  provided  on  the  tangential  walls  with  a  few  scattered, 
bordered  pits.    These  have  a  diameter  of  .016-.021  mm."  (Knowlton). 

Remains  silicified.    Specimens  represented  by  a  trunk  nearly  40  feet  long 

and  almost  2  feet  in  diameter. 
Potomac  Formation  at  Washington,  '^.C.  (Knowlton). 


I?~ 


21.  C.  Calli,  Knowlton 

"  Transverse.  The  annual  rings  are  very  distinct,  being  marked  by  a 
layer  of  fall  wood  6-15  or  more  cells  in  thickness.  These  cells  are 
very  thick-walled,  the  lumen  being  reduced  to  a  mere  line.  The  cells 
of  the  spring  wood  are  very  large  and  begin  abruptly  at  the  ring,  and 
gradually  diminish  in  .size  until  they  reach  and  pass  into  the  fall  wood. 
The  medullary  rays  as  seen  in  this  section  are  numerous  and  are  sepa- 
rated by  2-4  rows  of  tracheids. 

"Radial.  In  the  spring  and  summer  wood  the  tracheids  are  very  broad 
and  provided  with  2-3  rows  of  regularly  and  closely  packed  bor- 
dered 1  it ;.  These  pits  have  an  average  diameter  of  .012  mm.  and  an 
average  inner  diameter  of  .003  mm.  The  medullary  rays  are  thin- 
walled  and  in  some  ca.ses,  at  least,  provided  with  pits,  of  which  there 
are  usually  3  in  thickness  of  each  tracheid.  The  resin  tubes  consist  of 
a  chain  of  short,  rectangular  cells  ;  they  are  moderately  numerous. 

"  Tangential.  The  medullary  rays  are  arranged  in  a  single  series  of  super- 
imposed cells,  which  varies  from  2  to  25,  the  ordinary  number  being 
6-15.  The  tracheids  are  not  provided  with  pits  on  the  tangential 
walls"  (Knowlton). 

Remains  silicified. 

From  the  Tertiary  clays  of  Greene  County,  Arkansas  (Knowlton). 


11.  •  JUNIPERUS,  LiN\.     Plates  40  and  41 

Trans'i'erse.  Growth  rings  generally  narrow,  often  unconformable  and 
coalescent  on  the  narrow  side ;  the  summer  wood  usually  thin  but 
dense.  Resin  passages  wholly  wanting.  Re.sin  cells  rather  numerous, 
prominent,  and  chiefly  in  tangential  bands,  often  giving  rise  to  the 
appearance  of  secondary  growth  rings. 

Radial.  The  numerous  and  often  very  resinous  rays  chiefly  without  tra 
cheids.  Ray  cells  with  thin  and  entire  or  sometimes  coarsely  pitted 
terminal  walls ;  the  lateral  walls  with  bordered  pits.  Bordered  pits 
round  or  oval,  chiefly  in  i  row,  generally  numerous.  Tracheids  wholly 
without  spirals. 

Tangential.  F'u.siform  rays  wholly  wanting.  Ordinary  rays  i-seriate,  some 
times  2-seriate  in  part,  the  cells  oval,  chiefly  broad. 


JUNIPERUS 


245 


Synopsis  of  Species 

I.  Ray  cells  (tangential)  oval  to  round  or  transversely  oval, 
resinous,  conspicuously  broad 
Ray  cells  (radial)  resinous  throughout. 

4.  •  J.  californica. 

Ray  cells  (radial)  locally  resinous.     Rays  usually  higher  (tangential)  than 
in  No.  4 

5.  J.  utahensis. 

2.  Rays  (tangential)  rather  broad,  the  cells  oval  to  round,  chiefly 
round,  sometimes  in  pairs,  resinous 
Bordered  pits  (radial)  numerous,  usually  more  or  less  distant. 

Rays  (tangential)  rather  high,  more  or  less  2-seriate  or  the  cells  in 
pairs ;   the  cells  chiefly  very  round,  rarely  transversely  oval. 
9.  J.  pachyphlaea. 
Rays  (tangential)  low,  the  cells  rarely  in  pairs,  round  to  oval,  not  trans- 
versely oval 

1.  •  J.  virginiana. 

Bordered  pits  (radial)  numerous,  usually  crowded  into  compact  series. 
Rays  (tangential)  with  conspicuously  and  uniformly  rounded  cells. 

10.  J.  monosfwrma. 

3.  Ray  cells  (tangential)  chiefly  oval,  the  rays  low,  barely  resinous 
Summer  wood  of  2-4,  rarely  of  10,  tracheids. 

Pits  on  the  lateral  walls  of  the  ray  cells  chiefly  2  per  tracheid. 

11.  J.  occidentalis. 
Summer  wood  conspicuou.sly  thicker. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-4  per  tracheid. 

6.  J.  sabinoides. 
4.  Rays  (tangential)  narrow,  the  cells  oblong  to  oval,  chiefly  oblong 
Pits  on  the  lateral  walls  of  the  ray  cells  chiefly  2  per  tracheid.    Ray  cells 
resinous. 

Terminal  walls  of  the  ray  cells  strongly  pitted. 
Rays  with  narrow  tracheids. 

' .  J.  communis. 
Terminal  walls  of  the  ray  cells  thin  and  not  pitted. 

Rays  without  tracheids. 

3.  J.  rigida. 

Pits  on  the  lateral  walls  of  the  ray  cells  large,  2-4  per  tracheid,  obscurely 

and  irregularly  bordered. 

2.  J.  nana. 

I'its  on  the  lateral  walls  of   the  ray   cell.i    not  very  large,  chiefly  4  per 
tracheid.    Ray  cells  sparingly  resinous. 

8.  ].  sabina. 


'St 


<f^H 


-    I 

ill 


J  '5  -. 


246 


ANATOMY  OF  THE  GYMNOSPERMS 


I-  *  J-  Tirgiaiaiui,  Linn. 
A'ti/  Cedar.    Savin 

Transverse.  Growth  rings  usually  broad,  often  double  or  treble  The  thin 
summer  wood  rather  open  and  passing  gradually  into  the  broad  spring 
wood.  Spring  wood  rather  open,  the  tracheids  variable  with  medium 
walls,  in  regular  rows.  Resin  cells  rather  small  and  usually  disposed 
in  1-2  open  bands  chiefly  in  the  spring  wood.  Medullary  rays  not 
very  prominent  or  resinous,  rather  numerous,  i  cell  wide,  distant 
2-13  tracheids. 

Radial.  Ray  cells  not  very  resinous,  equal  to  5-10  spring  tracheids;  the 
upper  and  lower  walls  rather  thick,  unequal  and  remotely  pitted  • 
the  terminal  walls  thin,  straight,  and  entire,  rarely  curved  or  locally 
thickened ;  the  lateral  walls  with  small,  chiefly  bordered  pits  6  w 
broad,  chiefly  2,  njore  rarely  4,  per  tracheid,  the  orifice  narrow, 
inear-oblong.  Bordered  pits  round,  in  1  row,  sometimes  in  pairs, 
the  orifice  rather  large.  Pits  on  the  tangential  walls  of  the  summer 
lon*^  """>«™"s,  flat.    Resin  cells  about  20  /*  broad,  100-130  ^ 

Tangential.  Rays  sometimes  2-seriate  in  part,  low ;  the  cells  small,  nar- 
rowly oval  to  round,  chiefly  round,  thick-walled,  resinous. 

A  tree  20-30  m.  high,  with  a  trunk  .60-1.35  m-  in  diameter.  Wood  light, 
soft,  not  stronfe,  brittle,  very  close  and  straight  grained,  compact,  easily 
worked,  very  durable  in  contact  with  the  soil,  odorous. 

Relative  specific  gravity ^       g 

Approximate  relative  fuel  value .g", , 

Coefficient  of  elasticity  in  kilograms  on  millimeters'     '.     '.  670 

Ultimate  transverse  strength  in  kilograms      .     .  316" 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  6750" 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  .  2^76 

(Sargent)                                                                       •  01  ■ 

Nova  Scotia;  uncommon  about  Ottawa,  but  becoming  more  common 
westward  throughout  Ontario,  abundant  at  Bay  of  Quinte,  thence  south- 
ward, crossing  the  St.  Lawrence  River  midway  between  Montreal  and 
Lake  Ontario  (Macoun);  southward  from  New  Brunswick  to  Tampa 
Bay,  Florida ;  westward  through  Texas,  Nebraska,  Kansas,  and  Okla- 
homa to  the  looth  parallel,  thence  north  to  northern  Michigan,  Wiscon- 
sin, and  Minnesota ;  in  the  Pacific  region  through  the  mountains  of 
Colorado  and  British  Columbia  to  Vancouver  Island  (Sargent). 

Pleistocene  of  the  Don  Valley,  Toronto. 

Material  not  petrified,  but  remarkably  well  preserved  in  its  natural  state, 
and  exhibiting  the  characteristic  odor  when  cut. 


JUNIPERUS 


347 


2.  J.  Sana,  Willd. 

( "<»w  moH  Junifer 

Trann'trse.  Growth  rings  very  variable  and  unconformable,  the  tracheids 
very  small  throughout.  Summer  wood  thin,  of  3-6  tracheids,  rather 
open,  often  double,  the  transition  from  the  sprinjj  wood  gradual. 
Spring  wood  broad,  the  tracheids  squarish-hexagonal,  not  very  uni- 
form, small,  the  walls  medium,  the  general  den.sity  varying  greatly  in 
different  ring.s.  Medullary  rays  inconspicuous,  1  cell  wide,  distant  2-10 
rows  of  tracheids.    Kesin  cells  numeroas,  prominent,  distinctly  zonate 

Radial.  Rays  very  sparingly,  if  at  all,  resinous  throughout,  wholly  devoid 
of  tracheids.  Ray  cells  variable  in  height,  chiefly  straight  or  becom- 
ing contracted  in  the  summer  wood,  equal  to  7-8  spring  tracheids; 
the  upper  and  lower  walls  thin,  with  broad,  unequal,  and  usually 
rather  distant  pits;  the  terminal  walls  thin,  often  curved,  entire  or 
locally  thickened ;  the  lateral  walls  with  large,  very  prominent,  oval 
pits  with  an  obscure  and  unequal  border,  2-4,  or  in  the  summer  wood 
2,  per  tracheid.  Bordered  pits  numerous,  large,  as  broad  as  the  tra- 
cheid,  in  1  row.  Pits  on  the  tangential  walls  of  the  summer  tracheids 
numerous,  large,  and  open.  Resin  cells  20  /i  wide,  about  165  /i  long. 

Tangential.  Rays  rather  numeroas,  low  to  medium  ;  the  cells  equal,  rather 
uniform  and  oblong,  sometimes  oval,  the  walls  thin. 

Of  uncertain  range  in  the  northern  parts  of  the  continent ;  Lake  Mistas- 
sini ;  the  Shickshock  Mountains,  Gaspd ;  Bow  River,  Alberta ;  Rocky 
Mountains  from  Silver  City  westward  to  the  summit  of  the  Selkirks  in 
latitude  51°;  also  the  south  and  north  Kootenay  passes  (Macoun); 
Labrador  southward  to  Massachusetts  and  New  York,  thence  westward 
to  Michigan,  Colorado,  and  Utah  (Britton). 

3.  J.  rigida,  Sieb.  et  Zucc. 
/af.  =  Afuro 

Transr-erse.  Growth  rings  broad,  the  structure  rather  open  throughout. 
Summer  wood  very  thin,  of  3-4  tracheids,  the  transition  from  the 
spring  wood  rather  gradual.  Spring  tracheids  conspicuously  hex- 
agonal, rather  thin-walled,  uniform  in  regular  rows.  Medullary  rays 
not  very  prominent  or  resinous,  1  cell  wide,  distant  2-12  rows  of 
tracheids,  more  rarely  32.  Resin  cells  prominent,  usually  distant  in 
very  narrow  zones  of  occasional  growth  rings. 

Radial.  Rays  somewhat  resinous  throughout,  devoid  of  tracheids.  Ray 
cells  chiefly  .straight  or  somewhat  contracted  in  the  summer  wood ; 
the  upper  and  lower  walls  medium,  unequal,  distinctly  perforate  with 
broad  and  unequal  pits ;  the  terminal  walls  thin,  often  curved,  entire 
or  locally  thickened ;  the  lateral  walls  with  rather  large,  oval,  nar- 
rowly bordered  pits,  the  broadly  lenticular  orilice  becoming  oblong 
m  the  summer  wood,  1-2,  or  in  the  marginal  cells  4,  per  tracheid. 
Bordered  pits  round,  somewhat  distant  in  1  row,  not  very  numerous. 


248 


ANATOMY  OF  THE  GYMNOSPERMS 


Pits  on  the  tangential  walls  of  the  summer  tracheids  rather  numerous 
but  not  very  large  or  prominent.    Resin  cells  few,  15  u  wide,  185- 
240  fi  long. 
Tangential.  Rays  somewhat  numerous,  medium ;  the  cells  chiefly  equal, 
rather  uniform,  oblong,  more  rarely  oval  and  broader. 


4.  *  J.  callfonilca,  Carr. 

Juniptr 

Transverse.  Growth  rings  variable,  more  or  less  eccentric  and  often 
coalescent.  Summer  wood  thin,  chiefly  of  3-6  tracheids,  not  very 
dense,  pas.sing  somewhat  abruptly  into  the  broad  spring  wood. 
Spring  wood  rather  open,  the  tracheids  squarish,  the  walls  medium. 
Resin  cells  numerous  and  conspicuous,  chiefly  in  broad,  open  bands 
Medullary  rays  very  prominent  and  resinous,  1  cell  wide,  distant 
2-1 1,  rarely  17,  tracheids. 

Radial.  Ray  cells  very  resinous,  more  or  less  contracted  at  the  ends, 
equal  to  5-7  spring  tracheids;  the  upper  and  lower  walls  medium' 
and  entire  or  remotely  pitted,  becoming  conspicuously  thicker  at  the 
ends  of  the  cells;  the  terminal  walls  thin,  curved  and  entire  or 
straight,  locally  thickened  or  even  coarsely  pitted ;  the  lateral  walls 
with  oblong  pits,  chiefly  1,  or  in  the  marginal  cells  and  low  rays  2-4 
per  tracheid.  Bordered  pits  broadly  elliptical,  rather  numerous,  the 
orifice  rather  large.  Pits  on  the  tangential  walls  of  the  summer  tra- 
cheids numerous  and  prominent,  rather  large,  the  orifice  bell-shaped. 
Resin  cellj-  about  12.5-20/*  wide,  and  many  times  longer,  upwards 
of  2 1  s  /t. 

Tangential.  Rays  low  and  rather  broad,  very  resinous,  the  cells  from  nar- 
rowly oval  in  the  lowest  rays  to  round  or  more  rarely  transversely 
oval,  chiefly  round. 

A  small  tree  rarely  6-9  m.  high,  with  a  trunk  .30-60  m.  in  diameter. 
Wood  light,  soft,  very  close  grained  and  compact,  very  durable  in  contact 
with  the  soil. 


Relative  specific  gravity 
Percentage  of  ash  residue 
(Sargent) 


0.6282 
0-73 


Dry  slopes  and  plains  of  the  lower  Sacramento  River,  southward  through 
the  California  coast  ranges  to  Lower  California ;  spreading  inland  aloiii; 
the  coast  mountains  to  their  union  with  the  Sierra  Nevada,  throu(,'h 
which  it  ranges  northward  as  far  as  Kernville,  descending  to  2600  feet ; 
desert  .slopes  of  Tehachapi  .^Iountains,  and  abundant  on  the  northern 
foothills  and  on  the  seaward  slopes  of  the  San  Jacinto  and  Cuyamac.i 
ranges  (Sargent). 

From  the  Quaternary  deposits  (lowani")  of  the  Klamr!  .  -iver,  Orleans, 
Humboldt  County,  California,  in  blue,  sandy  silt  at  a  d.  ith  of  150  feet 
Material  very  slightly  silicified  and  in  a  good  state  of  prv  -  ervation. 


JUNIPERUS  2^5 

5.  J.  utabenaU,  Lemm. 

Juniftr 

^""'^r'M  ??/''  'k"^;'  ""'[y  ^='""^''='  '^''''"y  'l*'"-    •''"">"'"  *o«i  very 
thin,  of  2-4  trachcids,  the  transition  to  the  spriiir  wood  somewhat 

hexagon-.! ''1?'^  wo««„ra.her  open,  the  trachefds  Lu^.  ^uar^S 
fe  n  n  ""  "'^'^''^^  compressed,  rather  large,  the  wals  medium. 
ThhI^  ,  numerous,  conspicuous,  in  very  open  bands  in  both  the 
spring  and  summer  wood.    Medullary  rays  very  prominent  and  re,in 

tlnr.^  {  cells  more  conspicuously  contracted  at  the  ends  and  dis- 
tinctly less  resmous  than  in  the  preceding,  the  resin  chiefly  in  ^rmina^ 
masses,  equal  to  6-,o  spring  tracheids^  the  upper  and^ower  waUs 
un  forr^^'r  "'•^■'r^  »»  '»>e  ends  of  the  cells,  thickish  rSr 
uniform,  ob.scurely  pitted,  if  at  all;  the  terminal  walls  often  curved 
and  coarsely  pitted  ;  the  lateral  walls  with  oblong  pits,  often  wXan 
obscure  border,  chiefly  ,-2.  or  in  the  lowest  rtys  4  per  tracheid 
Fits  on  the  tangential  walls  of  the  summer  tracheids  veVy  numerous 
and  large,  but  less  open  and  prominent  than  in  J.  californica     Resin 

.^ttngtlirs.*''^'  '-''  "'"^-  '^'"^  -  "-^^-'^  ^'  ^«^  '^  -  - 

TaugeutiaL  Ra>^  somewhat  resinous,  the  cells  thick-walled,  chiefly  trans- 

versely   oval  or  oblong,  usually   broader  than    in   No   4  and  much 

shortened  vertically.  t  »  "  uiuun 

A  small  tree  6-9  m.  high,  with  a  trunk  .60-.90  m.  in  diameter.  Wood 
light,  soft,  close  grained,  compact,  very  durable  in  contact  with  the  soil. 

Relative  specific  gravity 

Percentage  of  ash  residue    .     .     . 

(Sargent)  

We.stem  base  of  Wa.satch  Mountains,  Utah,  to  eastern  California  and 
south  through  the  Great  Basin  to  southern  California;  the  San  Fran- 
cisco Mountains  of  eastern  Arizona  (Sargent). 

6.  J.  sabinoidet,  Ne^s. 

Cedar.     A'aci  Cedar 

^'""/n^nn"  ^T"'  n"^'  very  variable.  Summer  wood  rather  dense  and 
^n^"^  15  ""^'  ♦!:='*=^'^'ds,  often  double,  chiefly  much  less  than  the 
^pnng  wood,  into  which  it  passes  gradually  and  which  it  sometimes 
^"tt^  """"^  *''°**  "i"'^^^'  """"ewhat  open,  but  the  demarcation 
from  the  summer  wood  obscure.  Resin  cells  numerous,  not  verv 
resinous  or  prominent,  usually  in  somewhat  compact  zones,  chiefly  of 
the  summer  wood.  Medullary  rays  not  very  prominent,  1  cell  wide, 
distant  2-8,  rarely  12,  rows  of  tracheids 

Kadml.  Ray  cells  rather  resinous,  equal  to  5-10  spring  tracheids;  the 
S  '.  '7",^^'='  I^'her  thick,  variable,  frequently  pitted  he 
terminal    walls   thm   and   not   pitted   except  in    the  marginal  cells- 


0.5522 
0.75 


250  ANAIOMY  OF  THK  C.YMNOSF'EKMS 

the  lateral  walls  with  1-4  pilH  per  trachcid.  liordircd  pits  numerauK, 
In  I  row,  round  or  vertically  compresNed  in  compact  niws,  the  len- 
ticular orifice  large.  Pit*  on  the  tangential  walU  of  the  Hummer 
tracheids  numerous  and  prominent.  Kesin  cells  not  very  numerous, 
15-20  fi  wide  and  150-375  u  long. 
Tangtntial.  Rays  usually  very  low,  the  cells  oval  to  oblong,  not  broad, 
chiefly  oval,  barely  resinous. 

A  tree  11-15  m.  in  height,  with  a  trunk  upwards  of  .30  m.  in  diameter. 
Wood  light,  hard,  not  strong,  very  close  grained,  compact,  very  durable 
in  contact  with  the  soil. 

Relative  specific  gravity 0.6907 

Percentage  of  ash  residue 0.7 

Approximate  relative  fuel  value 68.75 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  734. 

Ultimate  transverse  strength  in  kilograms 200. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  8505. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  4464 

(Sargent)  ^^ 

Valley  of  the  Colorado  River,  western  Texas  (Sargent). 

7.  J.  communis,  Linn. 
Juniptr.     Ground  Ctdar 

Transverse.  Growth  rings  medium,  veiy  variable.  The  chiefly  thin  and 
dense  summer  wood  often  double,  sometimes  equal  to  the  spring 
wood,  into  which  it  passes  very  gradually,  the  line  of  demarcation 
obscure.  Tracheids  of  the  usu.illy  broad  spring  wood  small.  Resin 
cells  rather  numerous,  usually  not  very  prominent,  in  1-3  very  narrow 
zones  in  each  growth  ring,  the  contiguous  tracheids  rarely  becom- 
ing resinous  so  as  to  form  a  strongly  resmous  zone.  Medullary 
rays  numerous,  i  cell  wide,  distant  2-8,  or  more  rarely  jo,  rows  of 
tracheids. 

Radial.  Rays  uniformly  resinous  throughout,  tracheids  occasionally  pres- 
ent and  marginal.  Ray  cells  somewhat  contracted  at  the  ends,  equal 
to  5-6  spring  tracheids ;  the  upper  and  lower  walls  thick,  unequal, 
rather  frequently  pitted ,  the  terminal  walls  thin,  entire,  locally  thicli- 
ened  or  sometimes  coarsely  pitted ;  the  lateral  walls  with  unequally 
bordered,  oval  pits  having  a  large,  lenticular  orifice,  1-2  per  tracheid. 
Pits  on  the  tangential  walls  of  the  summer  tracheids  rather  numerous, 
not  very  large  or  prominent.  Resin  cells  12.5-15  /i  wide,  125-200 /* 
long.  Bordered  pits  round,  equal  to  the  tracheid,  in  i  row,  rather 
distant,  or  when  more  crowded  becoming  elliptical. 

Tangential.  Rays  numerous,  low,  narrow,  resinous ;  the  oblong  cells  thick- 
walled. 

A  prostrate  shrub  with  ascending  branches,  forming  dense  mats  upwards 
of  5-7  m.  in  diameter  and  1-1.30  m.  high. 


JUNIPERIS 


251 


Kroni  Labrador  lo  Jhc  Pacific  (Maeoun);  southward  to  New  Ji-rney  am! 
;'cnn.sylvaiiia:  wijt  ,ird  to  Michigan  and  wcMcrn  Ntl>ra»ka,  thentt; 
Kouthward  throuKh  the  Kmky  MounlaiiiH  to  New  Mexico  (Britton). 

8.  J.  Mbina,  Linn. 
Shrubby  Rtd  Ctdar 

Transverse.  Growth  rings  unequal,  often  coalencent  on  the  narrower  side. 
The  thin  .summer  wood  of  3-8  tracheidit,  rarely  forming  the  entire 
ring,  in  the  broader  ringH  l><.coming  double  or  treble.  Spring  wood 
open,  the  trachtid*  large  arid  thin-walled.  Keitin  cell.-i  not  very  numer- 
ous or  prominent,  chiefly  narrowly  zonate  in  the  spring  wood,  often 
.showing  extensive  but  local  aggregations  when  they  liecome  large, 
rounded  and  lootwly  grouped  in  irregular  masses  with  the  partial 
formation  of  resin  canals.  Medullary  rays  inconspicuous,  distant 
2-25,  rarely  37,  tracheids. 

Radial.  Ray  ceils  very  sjAaringly  resinous,  chiefly  straight,  equal  to  about 
S  spring  tracheids  ;  the  upper  and  lower  walls  thin  and  entire  or  with 
rather  distant  pits ;  the  terminal  walls  thin  and  locally  thickened  or 
coarsely  pitted  ;  the  lateral  walls  with  rather  prominent  pits  with  a 
broadly  lenticular  or  oval  orifice,  the  border  rather  obscure,  1-2, 
chiefly  4,  per  tracheid.  Bordered  pits  numerous,  as  broad  as  the  tra- 
cheids, generally  elliptical  in  i  compact  row,  the  orifice  large.  Pits 
on  the  tangential  walls  of  the  summer  tracheids  .somewhat  numerous 
and  prominent.    Kesin  cells  about  15  fi  wide,  125-150  /t  long. 

Tangential.  Rays  all  narrow,  the  cells  chiefly  narrowly  oval  to  oblong,  the 
walls  thin,  \  ariable  ;  when  of  a  single  cell,  the  latter  is  high,  lenticular. 

A  depressed,  usually  procumbent  shrub,  seldom  more  than  1.20  m. 
high  (Britton). 

On  exposed  slopes  and  river  banks  from  Anticosti,  Nova  Scotia,  New 
Brunswick,  Quebec,  and  Ontario,  across  the  prairie  region  to  the  sum- 
mit of  the  Rocky  Mountains  at  Kicking  Horse  Pass  (Maeoun);  from 
Maine,  westward  through  New  York,  Minnesota,  and  Montana  (Britton). 

9.  J.  pachyphlat,  Ton-. 
Juniper.     Checkered-Barked  Juniper 

Transverse.  Growth  rings  very  narrow  and  unequal,  eccentric.  Summer 
wood  dense  and  thin,  of  2-6  tracheids,  the  transition  to  the  spring 
wood  somewhat  gradual.  Spring  wood  somewhat  open,  the  tracheids 
in  regular  rows.  Resin  cells  numerous,  chiefly  in  the  spring  wood, 
irregularly  zonate.  Medullary  rays  very  prominent  and  resinous,  i 
cell  wide,  broad,  distant  2-8  tracheids. 

/Radial.  The  resinous  ray  cells  equal  to  4-13  spring  tracheids;  the  upper 
and  lower  walls  medium  to  thick,  entire  or  remotely  pitted ;  the  ter- 
minal walls  strongly  pitted  ;  the  lateral  walls  with  rather  conspicuous, 
lenticular  pits  about  1-2,  more  rarely  4,  per  tracheid.    Bordered  pits 


25a 


ANA'lt>MV  OF   1HE  GYMNOSPERMS 


It 

III 

ill 


ill 


round,  numeroun,  li«cominK  very  iimall  and  obKure  in  the  Rummer 
wood,  the  round  orifice  becuminK  lenticular  towards  the  Kummer  wood 
l'it!»on  the  iiinKcntial  walls  of  the  »ummer  tracheid*  numerou»,  medium^ 
t1.it.  Renin  relU  al>out  20  /i  wide,  i  65-400  ^  Irang. 
ranf;eHliitt.  Kays  medium,  often  3.»  riate  in  part,  the  celU  broadly  oval  or 
round,  rather  thick-walled. 

A  tree  6-15  m.  high  and  .60  m.  in  diameter. 

Wood  light,  soft,  not  strong,  brittle,  very  cIom  grained,  compact,  suscep- 
tible of  a  line  poliiih. 

Relative  specie  gravity q  -gjg 

Percentage  of  ash  residue 


(Sargent) 


0.1 1 


Mountains  of  western  Texas,  southern  New  Mexico,  and  Arizona  south  of 
latitude  34° ;  southward  into  Mexico  (Sargent). 

10.  J.  numotpenu,  Sarg. 

Juniptr 

TraHn>erse.  Growth  rings  chiefly  broad,  very  variable.  The  prominent 
but  u.Hu.illy  very  thin  summer  wood  dense,  of  3-7  trachelds.  often 
double  ;  the  transition  from  the  spring  wood  somewhat  gradual  Spring 
wood  somewhat  dense,  the  tracheids  variable.  Resin  cells  very  pronv 
ment  and  resinous,  numerous,  in  compact  zones  chiefly  in  the  sprintr 
wood.  Medullary  rays  very  numerous  and  prominent,  broad,  i  cell 
wide,  distant  i-io  rows  of  tracheids. 

Radial.  Ray  cells  resinous  throughout,  more  or  less  conspicuously  con- 
tracted at  the  ends,  equal  to  6-8  spring  tracheids ;  the  upper  and  lower 
walls  thick,  rather  uniform,  frequently  pitted;  the  terminal  walls 
coarsely  pitted  ;  the  lateral  walls  with  small,  round,  bordered  pits  with 
a  lenticular-oblong  but  small  orifice,  chiefly  2,  but  in  low  rays  and 
marginal  cells  often  upwards  of  6,  per  tracheid.  Bordered  pits  numer- 
OU.S  and  in  1  compact  row,  round  or  vertically  compressed,  neariy 
as  broad  as  the  tracheid.  Pits  on  the  tangential  walls  of  the  summer 
tracheids  very  numerous  but  small.  Resin  cells  about  i  s  u  wide.  200  u 
and  upwards  long. 

Tangential.  Rays  numerous,  rcsino  -,  low  ;  the  broad  cells  oval  or  round 
somewhat  uniform. 

A  stunte  i  tree  6-9  m.  high,  and  a  trunk  upwards  of  .60  m.  in  diameter. 

Relative  specific  gravity 0711Q 

Percentage  of  ash  residue „  78 

(Sargent)  '° 

Gravelly  slopes  between  3500  and  7000  feet  elevation,  eastern  base  of 
Pikes  Peak,  to  the  mountains  of  western  Texas  ;  through  New  Mexico 
and  southern  Arizona  to  southern  California  (Sargent). 


ABIKS 


'53 


11>  J.  cccl<fMM>,  Hook 

Tnnn.'trst.  (growth  ringi.  usually  verv  narrow ;  th,  den^L  summer  wood  of 
a-4,  rarely  lo,  trachcids,  passinK  ither  abruptly  into  th.  rather  open 
•pring  wc,«|  i  the  iracheid.  small  »nd  thitk-walled.  .Sprl„«  wood 
rather  optn,  but  the  tracheids  rather  ,m,.  '  ..nd  usually  much  rounded 
Kciin  fell,  abundant  and  ptomincnt,  thief!)  in  the  sumu,er  and  outer 
spring  wood  in  open  or  =  ompa.  (  /ones.  Medullary  ravs  numerous 
rather  promln^  nt,  not  very  reninou*.  i  ( dl  wide,  di»taii'(  i^  rarelv 
13,  rows  of  trachiids.  ' 

Ra^l.  Kay  cell,  verv  sparingly  re.inou.,  usually  straight  or  wmcwhat 
contracted  at  th-  en  Is.  equ.,1  to  ^  o  spring  tratheid.,;  th.  upper  jnd 
lower  wall,  thick.sh  entire  or  .bsuntly  pitted;  the  terminal  wall, 
•trongly  pitted  :  the  lateral  »  ais  ,Mth  small,  oval,  bordered  pi(«,  the 
orifice  o».long.  1-3,  m  -re  rare)  4,  |Hr  tracheiil  throughout.  Hordtred 
pit.  round,  numerous,  in  1  r.  «  becoming  obsci,  or  wantini;  in  the 
.ummcrwood.  Pits  on  the  tan  ntial  xv,,.,,  „(  „e  sun.mrr  tracheids 
numerous,  but  usually  small  and  often  oi^ure.  Kesm  cell,  numerous 
20^  wide,  140-275 /I  loHK.  ' 

TangtHtial.  Ray.s  generallv  lo\v,  of  a  few   ..Us  only       he  cells  round  K. 
oblong,  not  very  broa.!   chicily  oval. 

A  tree  6-15  m   high,  with  .    trunt  .  .:o  -mo  "  ,    i  di.^met  -  :  often  becoming 

a  low,  much-branched  shrui>. 
Wood  light,  soft,  very  close  grained,  r<-,i„.at,  vtu  „   rabic  in  .ontact  with 

the  soil. 

Kelatrve  specific  gravity o  C7fit 

Percentage  of  ash  residue  01 

(Sargent)  °'- 

Dry,  rocky  ridges  and  prairies  (,  the  Blue  Mountain.s  and  high  prairies  of 
eastern  Washington  and  Oregon  ;  the  Cascade  Mountains  of  Oregon  •  the 
valley  of  the  Klamath  River,  California,  and  south  along  the  hii;h  ridge, 
of  the  Sierra  Nevada  Mountainy  at  elevations  of  7000-10,000  feet,  to 
the  San  Bernardino  Mounuins  (Sargent). 


Ji± 


12.  •  ABIES,  Link.     Plates  42  and  43 

Tranrverse.  r.rowth  rings  ■  .ually  broad  with  no  very  clear  demarcation 
between  the  spring  and  summer  woods.  Resin  pa.s.sages  sometimes 
present  and  then  imperfectly  organized,  u.sually  In  somewhat  distant 
growth  rings  Resin  cells,  when  present,  remote  and  inconspicuous 
on  the  outer  face  of  the  summer  wood. 

/'.-v//«/.  Ray  tracheids  not  present  (except  A.  balsamea).  The  terminal 
wD,(s  of  the  ray  cells  usually  strongly  pitted,  especially  in  the  summer 
«oM.    Tracheids  wholly  without  spira!>. 

/■   ngeh,.al.  Fusiform  rays  wholly  wantini,'     I?  nys  narrow,  strictly  i-seriate. 


254 


ANATOMY  OF  THE  GYMNOSPERMS 


11^ 


Synopsis  of  Species 

I.  Resin  passages  present  but  imperfectly  developed* 
Ray  cells  (tangential)  all  broad,  oval,  or  round. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-3,  rarely  4,  per  tracheid. 
Tracheids  in  regular  rows. 

Resin  cells  on  the  outer  face  of  the  summer  wood. 

10.  A.  concolor. 

Resin  cells  wanting. 

8.  A.  bracteata. 

Pits  on  the  lateral  walls  of  the  ray  cells  chiefly  2,  rarely  3-4,  per  tracheid. 
Tracheids  in  regular  rows. 

Resin  cells  wanting. 

9.  A.  nobilis. 

Ray  cells  uniformly  narrow,  oblong. 

Pits  on  the  lateral  walls  of  the  ray  cells  obscurely  bordered,  greatly 
reduced  or  wanting  in  the  summer  wood,  1-4,  or  in  the  marginal 
cells  6,  per  tracheid. 

Resin  cells  wanting. 

11.  A.  firma. 

2.  Resin  passages  wholly  wanting 
Ray  tracheids  present,  few. 

Resin  cells  (transver.se)  wanting, 

Ray  cells  (tangential)  uniformly  narrow,  oblong. 

Pits  on  the  lateral  wallsof  the  ray  cells  i  -4,  rarely  8,  per  tracheid. 
4.  *  A.  balsamea. 
Ray  tracheids  wholly  wanting. 
Resin  cells  wanting. 

Ray  cells  (tangential)  uniformly  narrow. 

Fitson  the  lateral  wallsof  the  ray  cells  1-4,  rarely  8,  per  tracheid. 

4.  *  A.  balsamea. 
Pits  on    the    lateral  walls  of  the  ray  cells  obscurely  bor- 
dered, greatly  reduced  or  wanting  in  the  summer  wood, 
1-4,  or  in  the  marginal  cells  6,  per  tracheid. 
1 1 .  A.  firma. 
Pits  on  the  lateral  walls  of  the  ray  cells  more  or  less  obvi- 
ously bordered,  especially  in  the  summer  wood,  chiefly  2  per 

tracheid. 

1.  A.  Fra-seri. 

Ray  tells  (tangential)  variable,  from  round  or  oval  to  narrowly 

oblong. 

'  Species  included  in  this  section  should  also  be  looked  for  under  the  second 
section  with  the  same  differentiation. 


ABIKS 


255 


Pits  on  the  lateral  walls  of  the  ray  cells  1-4,  in  the  mar- 
ginal cells  rarely  5,  per  tracheid. 

Upper  and  lower  walls  of  the  ray  cells  strongly  pitted 
throughout. 

2.  A.  lasiocarpa. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-2,  or  in  the  mar- 
ginal cells  upwards  of  4,  per  tracheid. 

Upper  and  lower  walls  of  the  ray  cells  sparingly  pitted 
in  the  spring  wood. 

3.  A.  Veitchii. 

Resin  cells  scattering  on  the  outer  face  of  the  summer  wood. 
Ray  cells  broad  (tangential),  oval  to  round. 

Pits  on  the  lateral  walls  of  the  ray  cells  small,  round,  or 
oval,  at  first  obscurely  bordered,  but  toward  the  summer 
wood  with  a  distinct  border  and  narrow  orifice. 

Pits  on  the  lateral  walls  of  the  ray  tells  i  -4,  soon  becoming 
2,  and  in  the  summer  wood  i,  per  tracheid  throughout. 
Upper  and  lower  walls  of  the  ray  cells  thin,  not 
obviously  pitted. 

Ray  cells  (tangential)  verj-  broad  and  large. 
7.  A.  grandis. 
Pits  on  the  lateral  walls  of  the  ray  cells  1-2,  rarely  3, 
or  in  the  marginal  cells  sometimes  5,  per  tracheid. 
Upper  and  lower  walls  of  the  ray  cells  thick,  un- 
equal,  coarsely  but  very  unequally  pitted. 

Ray  cells  (tangential)  chiefly  ova!,  rarely  in 
pairs. 

6.  A.  amabilis. 
Pits  on  the  lateral  walls  of  the  ray  cells  chiefly  2,  more 
rarely  i  or  4,  or  in  the  summer  wood  i,  per  tracheid 
throughout. 

Upper  and  lower  walls  of  the  ray  cells  unequal, 
strongly  but  imperfectly  oitted  throughout. 
Ray  cells  (tangential)  round  or  oval,  not  very 
large. 

S-  A.  magniiica. 


1.  A.  Fraseri,  Poir. 

Balsimi.     She  lialsam 

Transverse.  Growth  rings  rather  thin,  variable,  the  structure  open  through- 
out. Summer  wood  very  thin,  of  2-6  tracheids,  passing  gradually 
into  the  spring  wood.    Spring  tracheids  rather  large  and  thin-walled, 


f  ■ 

^1 


f' 


256 


ANATOMY  OF  THE  GYMNOSPERMS 


squarish,  uniform,  in  very  regular  rows.  Resin  cells  none.  Resin- 
bearing  tracheids  few,  rather  prominent,  scattering  through  the  sum- 
mer wood,  more  rarely  in  the  spring  wood.  Medullary  rays  somewhat 
resinous  and  prominent,  i  cell  wide,  distant  2-15  rows  of  tracheids. 

Radial.  Medullary  rays  sparingly  resinous  throughout,  wholly  devoid  of 
tracheids.  Ray  cells  straight,  or  in  the  summer  wood  contracted  at 
the  ends,  equal  to  7-8  spring  tracheids ;  the  upper  and  lower  walls 
medium,  unequal,  somewhat  dista  tly  and  imperfectly  pitted  in  the 
spring  wood,  but  strongly  pitted  in  the  summer  wood ;  the  terminal 
walls  strongly  pitted ;  the  lateral  walls  with  small  pits  which  become 
conspicuously  bordered  in  the  summer  wood  where  the  orifice  is 
reduced  to  a  slit  and  the  pit  is  round,  1-2,  chiefly  2,  or  in  the  marginal 
cells  2-4,  per  tracheid.  Resin-bearing  tracheids  not  numerous,  the 
resin  sometimes  massive  in  the  summer  wood,  but  forming  a  periph- 
eral layer  in  the  spring  wood.  Bordered  pits  elliptical,  in  i  row  or 
sometimes  in  pairs.  Pits  on  the  tangential  walls  of  the  summer 
tracheids  somewhat  numerous  but  small  and  flat. 

Tangential.  Rays  small  to  medium,  the  cells  narrow,  rather  uniform,  oval 
to  oblong. 

A  tree  18-24  m.  high  and  upwards  of  .60  m.  in  diameter. 
Wood  very  light,  soft,  not  strong,  coarse  grained,  compact. 

Relative  s[>eciflc  gravity o-3S'i5 

Percentage  of  ash  residue 0.54 

Approximate  relative  fuel  value 3546 

Coefficient  of  elasticity  in  kilograms  on  millimeters   .  972. 

Ultimate  transverse  strength  in  kilograms 273. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  .  5557. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms        .     .  1048. 
(Sargent) 

High  mountains  of  North  Carolina  and  Tennessee,  forming  somewhat 
extensive  forests  on  moist  slopes  between  5000  and  6500  feet  (Sargent). 


2.  A.  lesiocarpa,  Nutt. 

Mountain  Balsam.     Balsam  Fir 

Transverse.  Growth  rings  narrow,  uniform,  the  structure  open  throughout. 
Summer  wood  very  thin,  rarely  upwards  of  14  tracheids,  the  transition 
to  the  spring  wood  gradual.  Spring  wood  of  large,  squarish  tracheids 
with  rather  thin  walls,  uniform  in  regular  rows.  Resin  cells  and  resin- 
ous tracheids  wholly  wanting.  Medullary  rays  not  prominent,  barely 
if  at  all  resinous,  I  cell  wide,  distant  2-8,  more  rarely  ij,  tracheids. 

Radial.  Rays  very  sparingly  resinous,  wholly  devoid  of  tracheids.  Ray 
cells  more  or  less  con.spicuously  contracted  at  the  ends,  equal  to  about 
7  spring  tracheids;  the  upper  and  lower  walls  thick,  unequal,  and 
strongly  pitted  throughout ;  the  terminal  walls  thin,  often  devoid  of 
pits ;  the  lateral  walls  with  obscurely  bordered  pit.s,  the  large  orifice 
lenticular,  variable,  1-4,  or  in  the  marginal  cells  rarely  5,  per  tracheid, 
and  distinctly  bordered,  in  the  summer  wood  reduced  to  1  per  tracheid 


ABIES  257 

and  distinctly  bordered.  Bordered  pits  elliptical,  in  1  row,  nearly 
the  diameter  of  the  tracheid.  Pits  on  the  tangential  walls  of  the 
summer  tracheids  rather  numerous,  not  very  large.  Resin  cells  and 
resinous  tracheids  wholly  wanting. 
Taugential.  Rays  medium,  the  cells  variable,  from  round  or  broadly  oval 
to  narrowly  oblong. 

A  tree  20-40  m.  high,  with  a  trunk  upwards  of  .60  m.  in  diameter. 
Wood  very  light,  soft,  not  strong,  rather  close  grained,  compact. 

Relative  specific  gravity 0.3476 

Percentage  of  ash  residue 0.44 

Approximate  relative  fuel  value 34-6 1 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  762. 

Ultimate  transverse  strength  in  kilograms 202. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  4829. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  1015. 
(Sargent) 

Summit  of  House  Mountain,  south  of  Lesser  Slave  Lake ;  abundant  in 
Bow  River  Pa.ss  on  mountain  slopes  5000-7000  feet  elevation,  extend- 
ing on  the  line  of  the  Central  Pacific  Railroad  from  Castle  Mountain 
to  Selkirk  Summit ;  abundantly  in  the  Gold  and  Selkirk  ranges,  and  in 
the  Rocky  Mountain  region  east  of  McLeod's  Lake  ;  elsewhere  in  the 
northern  portion  of  the  interior  plateau  it  occurs  in  scattering  groves, 
generally  in  localities  nearly  reaching  or  surpassing  4000  feet,  but  even 
in  low  valleys  in  the  eastern  portion  of  the  coast  ranges  ;  damp  situations 
in  the  country  between  Lesser  Slave  Lake  and  the  Athabasca  River ; 
high,  cool  valleys  in  the  Rocky  Mountains,  southward  to  the  49th  par- 
allel, reaching  upward  to  the  timber  line  (Macoun) ;  valley  of  the  Stakhin 
River  in  Alaska,  in  latitude  60°  N. ;  through  the  Blue  Mountains  of 
Oregon  and  the  ranges  of  Idaho,  Montana,  Wyoming,  Utah,  and  Col- 
orado; on  mountain  slopes  and  canons  from  4000  (British  Columbia) 
to  12,000  feet  (Colorado);  rarely  forming  the  prevailing  forest  growth 
(Sargent). 

3.  A.  Veitchii,  Lindl. 

/up.  =  Shirabi 

Transverse.  Growth  rings  very  variable,  often  very  narrow.  Summer  wood 
prominent  but  very  narrow,  of  3-5  squarish  tracheids,  the  structure 
open,  or  again  broad  and  .somewhat  exceeding  the  spring  wood,  with 
the  structure  rather  open  but  the  tracheids  strongly  rounded  ;  transition 
to  the  spring  wood  gradual.  Spring  wood  open,  the  tracheids  rather 
large,  .squarish,  and  thin-wallcd,  uniform  in  regular  rows.  Resin  cells 
and  resinous  tracheids  wanting.  Medullary  rays  not  prominent,  1  cell 
wide,  distant  1-20  rows  of  tracheids. 

Kiuiial.  Rays  somewhat  resinous  in  part,  and  wholly  devoid  of  tracheids. 
Ray  cells  chietiy  straight,  equal  to  7-8  spring  tracheids,  or  in  the 


I 

m 


253 


ANATOMY  OF  THE  GYMNOSPERMS 


summer  wood  becoming  very  much  shorter  ;  the  upper  and  lower  walls 
medium,  unequal,  the  narrow  pits  not  very  numerous,  except  in  the 
summer  wood,  often  imperfectly  formed ;  the  terminal  walls  closely 
pitted,  becoming  more  prominent  in  the  summer  wood ;  the  lateral 
walls  with  narrowly  bordered  oval  pits,  1-2,  or  in  the  marginal  cells 
upwards  of  4,  per  tracheid,  the  orifice  broadly  lenticular  or  oval.  Bor- 
dered pits  round  or  elliptical,  numerous  in  I  row,  variable,  but  chiefly 
two  thirds  the  diameter  of  the  tracheid,  the  large  orifice  round.  Pits  on 
the  tangential  walls  of  the  .summer  tracheids  few,  small,  rather  open. 
Resin  cells  and  resinous  tracheids  wholly  wanting. 
Tangential.  Rays  not  very  numerous,  medium  to  high,  somewhat  resinous, 
strictly  1 -seriate ;  the  cells  somewhat  unequal  and  variable,  chietly 
round  or  oval,  sometimes  oblong. 


ii 


4.  •  A.  balaamea,  Mill. 

Balsam  Fir.     Balm-of-GiUad  Fir.     Canada  Balsam  Fir 

Transverse.  Growth  rings  thick.  Summer  wood  thin,  often,  passing  very 
gradually  into  the  spring  wood.  Spring  wood  very  open,  the  large 
tracheids  squarish-hexagonal,  thin-walled,  uniform  in  regular  rows. 
Resin  cells  wanting.  Medullary  rays  not  numerous  or  prominent, 
1  cell  wide,  distant  2-8,  rarely  1 2,  rows  of  tracheids. 

Radial.  Ray  tracheids  few,  narrow,  and  very  unequal ;  the  rays  barely 
resinous.  Ray  cells  conspicuously  contracted  at  the  ends  and  equal 
to  2-6  spring  tracheids ;  the  upper  and  lower  walls  medium,  unequal, 
somewhat  distantly  and  finely,  but  often  imperfectly,  pitted ;  the  ter- 
minal walls  coarsely  pitted,  especially  in  the  summer  wood  ;  the  lateral 
walls  with  .small,  round  or  oval  pits,  2-4,  more  rarely  upwards  of  8,  per 
tracheid.  Bordered  pits  elliptical,  large,  one  half  the  diameter  of  the 
tracheid,  chiefly  rather  scattering,  in  i  row  or  often  in  pairs,  and 
more  or  less  imperfectly  2-rowed.  Pits  on  the  tangential  walls  of  the 
summer  wood  not  numerous,  chiefly  quite  small. 

Tangential.  Rays  medium,  the  cells  narrow,  uniform,  oval  to  oblong. 

A  tree  21-27  m.  high,  with  a  trunk  upwards  of  .60  m.  in  diameter. 
Wood  very  light,  soft,  not  strong,  coarse  grained,  compact,  not  durable. 

Relative  specific  gravity 0.3819 

Percentage  of  ash  residue 0.45 

Approximate  relative  fuel  value 38.03 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  819. 

Ultimate  transverse  strength  in  kilograms 220. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  5851. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  1202. 
(Sargent) 

Abundant  in  swamps  throughout  the  eastern  provinces  of  Canada,  north- 
ward to  James  Bay  and  westward  to  the  Athabasca  River  in  latitude  58" 
(Macoun);  southward  through  the  northern  United  States  to  Pennsyl- 
vania, and  along  the  Allegheny  Mountains  to  the  high  peaks  of  Virgini.i ; 


■  M 


ABIES  259 

westward  through  central  Michigan  and  Minnesota  and  northward  along 

the  eastern  slope  of  the  Rocky  Mountains  (Sargent). 
Pleistocene  of  the  Scarborough  Period  at  Scarborough,  Ontario. 
Material  altered  by  decay,  but  otherwise  in  original  condition  and  not 

petrified. 

6.  A.  nugnillca,  A.  Murr. 
Ktd  Fir 

Transverse.  Growth  rings  rather  broad.  The  summer  wood  upwards  of 
one  third  the  growth  ring,  the  structure  open  throughout,  but  the  most 
recent  tracheids  much  compressed  radially,  transition  to  the  spring 
wood  very  gradual.  Spring  wood  open,  the  large,  con.spicuousiy 
squarish  tracheids  uniform  in  very  regular  rows,  thin-walled.  Resin 
cells  present  on  the  outer  face  of  the  summer  woo<l,  where  they  are  to 
be  distinguished  by  their  thin  walls  and  somewhat  advanced  position. 
Medullary  rays  prominent,  sparingly  resinous,  1  cell  wide,  distant  2-10 
rows  of  tracheids. 

Radial.  Rays  sparingly  resinous  throughout  and  wholly  devoid  of  tracheids. 
Ray  cells  straight  throughout,  equal  to  7-9  spring  tracheids,  l)ecoming 
much  shorter  in  the  summer  wood ;  the  upper  and  lower  walls  thick, 
unequal,  and  strongly  but  imperfectly  pitted  throughout ;  the  terminal 
walls  sparingly  pitted  in  the  spring  wood,  but  becoming  strongly  pitted 
in  the  summer  wood ;  the  lateral  walls  with  small,  obscurely  bordered 
pits,  at  length  becoming  conspicuous  and  round  with  a  prominent 
border  and  slitlike  orifice  toward  the  summer  wood,  chiefly  2,  more 
rarely  i  or  4,  in  the  summer  wood  reduced  to  1,  per  tracheid  through- 
out. Bordered  pits  in  i  row,  elliptical,  becoming  much  .smaller 
toward  the  summer  wood,  where  the  round  orifice  liecomcs  narrow 
and  prolonged,  coalescing  to  form  spiral  striations.  Pits  on  the  tan- 
gential walls  of  the  summer  tracheids  numerous  but  flat  and  small, 
sometimes  present  on  the  tangential  walls  of  the  earliest  .spring 
tracheids.  Resin  cells  few,  on  the  outer  face  of  the  summer  wood, 
nonresinous  and  distinguished  by  the  transverse  septa  without  bor- 
dered pits;  narrow  and  very  long,  usually  about  20-25  /*  wide, 
350-435  M  or  more  long. 

Tangential.  Rays  high,  occasionally  2-seriate  in  part,  the  cells  uniformly 
broad,  round,  and  large  or  oval,  sometimes  sparingly  resinous. 

A  large  tree  61-76  m.  high,  with  a  trunk  2.40-3  m.  in  diameter. 
Wood  light,  soft,  not  strong,  rather  clo.se  grained,  compact,  satiny,  durable 
in  contact  with  the  soil,  liable  to  twist  and  warp  in  seasoning. 

Relative  sjjecific  gravity 0.4701 

Percentage  of  ash  residue 0.30 

Approximate  relative  fuel  value .  46.87 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  662. 

Ultimate  transver.se  strength  in  kilograms 299. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  6963. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  1545. 
(Sargent) 


26o 


ANATOMY  OF  THE  GYMNOSPERMS 


California,  Mt.  Shasta,  soutli  along  the  western  slopes  of  the  Sierra  Nevad.is 
to  Kern  County;  forming  extensive  forests  between  4900  and  8000  feet 
elevation ;  becoming  less  common  south  of  Mt.  Shasta,  and  reaching  an 
extreme  elevation  of  10,000  feet  (Sargent). 


6.  A.  amabUis,  Forbes 
IVAiU  Fir 

Transverse.  Growth  rings  narrow,  the  structure  usually  very  open  through- 
out. Summer  wood  upwards  of  one  half  the  spring  wood,  into  which 
it  passes  very  gradually.  Spring  tracheids  large,  thin-walled,  very 
squarish,  and  uniform  in  regular  rows.  Resin  cells  few  and  widely 
scattering  on  the  outer  face  of  the  summer  wood,  where  they  may  l)e 
distinguished  by  (i)  the  sieve-plate  structure  of  the  terminal  wall,  and 
(2)  their  often  advanced  position.  Medullary  rays  rather  prominent, 
not  resinous,  i  cell  wide,  numerous,  distant  2-9  rows  of  tracheids. 

Radia!.  Rays  nonresinous,  wholly  devoid  of  tracheids.  Ray  cells  chiefly 
straight  except  in  the  summer  wood,  equal  to  3-7  spring  tracheids, 
becoming  much  shorter  in  the  summer  wood;  the  upper  and  lower 
walls  thick,  unequal,  and  coarsely  but  very  unequally  pitted  through- 
out ;  the  terminal  walls  strongly  pitted  throughout ;  the  lateral  wall.s 
with  small,  round  or  oval  pits,  which  toward  the  summer  wood  show  a 
prominent  and  broad  border,  and  the  broadly  lenticular  orifice  becomes 
reduced  to  a  slit,  1-2,  rarely  3,  or  in  the  marginal  cells  .sometimes  5, 
per  tracheid.  Bordered  pits  in  i  row,  sometimes  in  pairs,  variable, 
elliptical.  Pits  on  the  tangential  walls  of  the  summer  tracheids 
numerous  and  rather  small,  but  broadly  lenticular,  open.  Resin  cells 
frequently  present  on  the  outer  face  of  the  summer  wood,  sometimes 
conterminous  with  similar  tracheids ;  usually  very  narrow  and  long, 
12.5-25  fi  wide,  and  upwards  of  600  y.  long. 

Tangential.  Rays  medium  to  high,  the  cells  uniform,  chiefly  oval,  more 
rarely  round  or  narrowly  oval,  sometimes  in  pairs. 

A  tree  30-45  m.  high,  with  a  trunk  upwards  of  1.20  m.  in  diameter. 
Wood  light,  hard,  not  strong,  close  grained,  compact. 


42:S 

23 

IS 


Relative  specific  gravity 

Percentage  of  ash  residue 

Approximate  relative  fuel  value 4 

Coefficient  of  elasticity  in  kilograms  on  millimeters     .     .     1260 

Ultimate  transverse  strength  in  kilograms 338 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms     7480 
Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .     1029 
(Sargent) 

Valley  of  the  Fraser  River  and  probably  farther  north  ;  south  along  tlit 
Cascade  Mountains  of  Washington  and  Oregon  (Sargent). 


ABIES 


a6i 


7.  A.  gnndU,  Lindl. 

It'Aite  Fir 

Transverse  Growth  rinRs  usually  very  broad,  the  structure  rather  open 
throughout.  Summer  wood  prominent,  upwards  of  one  eighth  to  one 
fourth  the  very  broad  spring  wood,  into  which  it  passes  gradually, 
the  tracheids  very  unequal.  Spring  tracheids  very  large,  thin-walled, 
hexagonal,  in  regular  rows,  rather  uniform.  Resin  cells  few  and  scat- 
tering on  the  outer  face  of  the  summer  wood,  nonresinous,  distinguished 
by  (I)  the  sieve-plate  structure  of  the  terminal  walls,  and  (2)  their 
somewhat  advinced  position.  Resin-bearing  tracheids  more  or  less 
numerous  and  scattering  through  the  summer  wood.  Resin  passages 
wholly  wanting.  Medullary  rays  rather  prominent  and  resinous,  espe- 
cially m  the  summer  wood,  1  cell  wide,  distant  2-8,  or  rarely  10-12 
rows  of  tracheids.  '  ' 

Radial.  Rays  more  or  less  resinous  throughout.  Ray  cells  straight,  becom- 
ing  contracted  at  the  ends  in  the  summer  wood,  equal  to  4-6  spring 
tracheids ;  the  upper  and  lower  walls  thin  and  entire  or  sparingly  and 
imperfectly  pitted ;  the  terminal  walls  at  first  barely  if  at  all  pitted 
but  at  length  coarsely  pitted  in  the  summer  wood;  the  lateral  walls 
with  prominent  but  small  oval  pits,  with  an  obscure  border,  the  latter 
becoming  prominent  toward  the  summer  wood,  where  the  broadly  len- 
ticular orifice  becomes  oblong,  1-2  throughout,  or  more  rarely  4-6  in 
the  marginal  cells.  Bordered  pits  rather  numerous  in  1  row,  ellip- 
tical but  variable,  the  orifice  large.  Resin-bearing  tracheids  rather 
numerous  and  chiefly  in  contact  with  the  rays,  very  resinous.  Resin 
cells  on  the  outer  face  of  the  summer  wood  rather  prominent,  long, 
and  narrow,  nonresinous,  about  equal  to  20 /n  wide  and  135-31011 
long.  Fits  on  the  tangential  walls  of  the  summer  tracheids  somewhat 
numerous,  rather  small  and  flat. 

TiVij^ential.  Rays  rather  numerous,  low  to  high,  broad,  the  rather  large 
cells  more  or  less  unequal,  chiefly  broadly  oval,  often  squarish,  fre- 
quently resinous. 

A  tree  61-92  m.  high,  with  a  trunk  .90-1.50  m.  in  diameter. 
Wood  light,  soft,  not  strong,  coarse  grained,  compact. 

Relative  specific  gravity 03545 

Percentage  of  ash  residue o  49 

Approximate  relative  fuel  value .     .     .  35.08 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  958^ 

Ultimate  transverse  strength  in  kilograms 211. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  6255. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  810 
(Sargent) 

\ancouver  Island,  south  to  Mendocino  County,  California,  near  the  coast ; 
interior  valleys  of  western  Washington  and  Oregon,  south  to  the  Umpqua 
Kiver,  Ca.-  ade  Mountains  below  4000  feet  elevation  ;  Blue  Mountains  of 
Oregon  ;  Bitter  Root  Mountains  of  Idaho;  western  slopes  of  the  Rocky 
Mountains  of  northern  Montana  (Sargent). 


262 


ANATOMY  OF  THE  (iYMNOSPERMS 


|l>' 


It! 


8.  A.  bracteaU,  Nutt. 

Silver  hir 

TraHsi'trse.  Growth  rings  broad.  Summer  wood  prominent,  dense,  one 
third  the  spring  wood,  into  which  it  passes  somewhat  gradually.  Sprinj; 
wood  rather  open,  the  tracheids  large  and  thin-walled,  squarish-hex- 
agonal, rather  uniform  in  regular  rows.  Kesinous  tracheids  wholly 
wanting.  Kesin  cells  sometimes  present  and  then  forming  imperfectly 
organized  resin  canals  in  a  somewhat  continuous  zone,  within  or  near 
the  summer  wood  of  distant  growth  rings.  Medullary  rays  prominent 
and  somewhat  resinous,  especially  in  the  summer  wood,  I  cell  wide. 

Radial.  Kays  somewhat  resinous  throughout,  especially  in  the  summer 
wood,  wholly  devoid  of  tracheids.  Kay  cells  .straight  or  barely  fusi- 
form except  in  the  summer  wood,  where  they  are  strongly  contracted 
at  the  ends ;  equal  to  about  5  spring  tracheids ;  the  upper  and  lower 
walls  rather  thin,  unequal,  rather  distantly  pitted  except  in  the  sum- 
mer wood,  where  the  pits  are  numerous,  or  again  in  the  spring  wood 
locally  numerous ;  the  terminal  walls  thin,  often  devoid  of  pits  except 
in  the  summer  wood ;  the  lateral  walls  with  prominent,  round  or 
broadly  oval  pits,  chiefly  1-3,  or  in  the  marginal  cells  4,  per  tracheid. 
Bordered  pits  numerous,  chiefly  elliptical  in  i  row,  or  often  in  pairs 
so  that  they  become  more  or  less  2-rowed.  Pits  on  the  tangential 
walls  of  the  summer  wood  numerous  and  extending  well  into  the 
interior.  Kesin  cells  short-cylindrical,  united  to  form  short  resin  sacs 
on  the  outer  face  of  the  summer  wood. 

Tangential.  Rays  medium  to  high ;  the  cells  chiefly  broad,  oval,  often 
resinous  and  sometimes  in  pairs  of  much  smaller  cells. 

A  tree  41-61  m.  in  height  and  with  a  trunk  .90-1.20  m.  in  diameter. 
Wood  heavy,  not  hard,  coarse  grained,  compact. 


Relative  specific  gravity 
Percentage  of  ash  residue 
(Sargent) 


0.6783 
2.04 


Santa  Lucia  Mountains  of  California,  from  the  northern  boundary  of 
San  Luis  Obispo  County,  about  40  miles  northward  ;  on  moist,  cold  .soil, 
occupying  four  or  five  cafions  at  3000-6000  feet  elevation,  generally  west 
of  the  summit  of  the  range  (Sargent). 

9.  A.  nobilis,  Lindl. 

Red  Fir.     Larch 

Transverse,  (growth  rings  rather  broad.  The  summer  wood  prominent, 
hro.i'l,  upwards  of  one  half  the  .spring  wood,  the  structure  ihicriy 
open,  but  beioming  rather  dense  on  the  outer  face  of  the  growth  rini;; 
transition  to  the  spring  wood  gradual.  Spring  tracheids  rather  l,ir).;t' 
and  thin-walled,  squarish-hexagonal,  toward  the  summer  wood  JKccim- 
ing  unequal  and  in  more  or  less  irregiilar  rows.    Ke.sin  cells  locali/til 


ABIKS  263 

to  form  imperfect  resin  canals*  in  a  more  or  less  continuous  zone  in 
the  summer  wood  of  distant  growth  rings.  Medullary  rays  prominent, 
somewhat  resinous,  i  cell  wide,  distant  i-S  rows  of  trachcids. 

Radial.  Rays  more  or  less  resinous  throughout,  wholly  devoid  of  ir.i 
cheids.  Ray  cells  chietly  straight,  becoming  conspicuously  fusiform 
in  the  summer  wood,  equal  to  about  8-1 1  spring  tracheids  ;  the  uppir 
and  lower  walls  medium,  unequal,  more  or  lcs,s  strongly  pitted  through- 
out ;  the  terminal  walls  strongly  pitted ;  the  lateral  walls  with  round 
or  oval,  conspicuously  bordered  pits,  the  orifice  lenticular  or  oblong, 
1-2,  or  in  the  marginal  cells  rarely  3-4,  per  tracheid.  Uordered  pits 
in  I  row,  sometimes  in  pairs,  round,  the  orifice  large.  Fits  on  the 
tangential  walls  of  the  summer  tracheids  minute.  Resin  cells,  when 
present,  short-cylindrical  and  united  to  form  short  resin  sacs  within 
the  summer  wood  of  distant  growth  rings. 

Tangential.  Rays  medium  to  high,  the  cells  often  resinous,  chiefly  broad 
but  variable  from  round  to  oval  and  oblong,  unequal,  often  in  pairs. 

A  large  tree  61-92  m.  high,  with  a  trunk  2.40-3  m.  in  diameter. 
Wood  light,  hard,  strong,  rather  close  grained,  compact. 

Relative  specific  gravity 0.4561 

Percentage  of  ash  residue \     \  0.3, 

Approximate  relative  fuel  value .     .        45^46 

Coefficient  of  elasticity  in  kilograms  on  millimeters     .     .  1277. 

Ultimate  transverse  strength  in  kilograms 368! 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  7256. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms     .     .  1017 

(Sargent)  *  ^  '' 

Oregon,  Cascade  Mountains  from  the  Columbia  River  south  to  the  valley 
of  the  upper  Rogue  River,  and  along  the  .summits  of  the  Coast  Range 
from  the  Columbia  to  the  Nestucca  River  (Sargent). 


10.  A.  concolor,  Lindl.  and  Gordon 
White  Fir.    lialsam  Fir 

Transverse.  Growth  rings  broad,  the  structure  rather  open  throughout. 
Summer  wood  prominent,  thin,  upward.s  of  one  third  the  spring  wood, 
into  which  it  passes  very  gradually.  Spring  tracheidh  medium,  squar- 
ish, thin-walled,  and  uniform  in  somewhat  regular  rows.  Resin  pas- 
.sages  prominent  and  rather  nunerous  but  imperfectly  formed,  very 
variable,  and  often  large,  forming  more  or  less  continuous  series 
within  the  summer  wood,  often  of  distant  growth  rings.  Resin  cells 
few,  nonresinous,  distant  on  the  outer  face  of  the  summer  wood  and 
distinguished  by  (1)  the  siive-plate  structure  of  the  terminal  wall,  and 
(2)  their  somewhat  advanced  position.  Medullary  r.iys  rather  promi- 
nent and  somewhat  resinous,  especially  in  the  summer  wood  :  1  cell 
wide,  distant  2-7,  rarely  10,  rows  of  tracheids. 

Radial.  Rays  somewhat  resinous,  especially  in  ihc  summer  wootl.  Ray 
cells  conspicuously  contracted  at  the  ends   throuKhout  and  equal  to 


11 


,i 
Iff 
M 


Si 


264  ANATOMY  OF  THE  GYMNOSPERMS 

(>-ii  spring  tracheids,  f)eron»inK  shorter  in  the  suntmcr  wood;  the 
upper  and  lower  walls  r.iilu  r  thick,  untitual,  and  conspicuously  pitted 
throughout ;  jhe  terminal  wall>  rather  sparingly  pitted,  especially  in 
the  spring  wood '.  !he  lateral  walls  with  round  or  elliptical,  small, 
obscurely  Iwrdered  pits,  which  becfwne  distinctly  bordered  toward  the 
summer  wood,  where  the  broadly  lenticular  orifice  becomes  oblong 
or  hnally  slitlike,  1-3  per  tracheid  throughout  the  spring  wood,  becom- 
ing I  in  the  summer  wootl.  Bordered  pits  rather  numerous  in  i  row, 
elliptical  (i  round.  Pits  en  the  tangential  walls  oi  the  summer  tra- 
cheids  rather  numerous  but  not  very  large,  flat.  I'its  rarely  on  the 
tangential  w.ills  of  the  ear  ier  spring  tracheids.  Resin  cells  rarely  to 
be  stcn.  Re.s-  passages i..i)crfectly  formed  of  short,  rylina.ical  resin 
cells,  in  interrupted  series. 
TaMf;tittial.  Rays  num>  rous,  medium  to  high,  not  very  broad  ;  the  cells 
chiefly  uniforM',  oval,  scj  letimts  round  or  oblong,  r.rely  large. 

A  tree  30-40  m.  in  height,  witu  a  trunk  1. 20-1. 50  m.  in  diameter. 
Wood  very  light,  soft,  not  strong,  coar.se  grained,  compact. 

Relative  specihi;  gravity 0.3638 

Percentage  of  ash  residue 0.85 

Approximate  relative  fiul  value  .           3607 

Coeftiriint  of  elasticity  in  kilograms  on  millimeters      .     .  909. 

Ultimate  transverse  strength  in  kilograms 300. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  6237. 

Resistance  to  indentatiin  to  1.27  mm.  in  kilograms      .     .  1248. 
(Sargent) 

Moist  slopes  and  canons  between  3000  ana  9c 00  feet  ekvation,  reach- 
ing its  greatest  development  in  the  California  Sierras;  orthern  slopis 
of  the  Siskiyou  Mountains  of  Oregon  ;  south  along  the  western  slope  of 
the  Sierra  Nevadas  to  San  Bernardino  and  San  Jacinto  Mountains  of 
California;  the  high  mountains  of  Arizona  to  the  Mogollon  Mountains 
of  New  Mexico  ;  northward  to  Pikes  Peak  and  the  Wasatch  Mouii 
tains  of  Utah  (Sargent). 

11.  A.  firmc,  Sieb.  et  Zucc. 
Jap.  =  Afomi 

Transverse.  Growth  rings  broad,  the  dense  summer  wood  about  nnu 
fourth  the  spring  wood,  into  which  it  passes  gradually.  Spring  wood 
open,  the  tracheids  thin-wallcd,  in  very  regular  rows,  uniform,  larj;t. 
Resin  cells  and  resinous  tracheids  wanting.  Medullary  rays  ratlur 
prominent  and  sparingly  resinou.s,  1  cell  wide,  distant  2-10  rows  ol 
tracheids.  Resin  canals  present  but  imperfectly  organized,  forming' 
local  or  sometimes  extensive  tangential  rows  on  the  outer  face  ol  iIk 
summer  wood  of  distant  growth  rings. 

Radial.  Medullary  rays  sparingly  resinous,  devoid  of  tracheids.  K.iy 
cells  straight,  equal  to  5-10  spring  tracheids,  in  the  summer  wood 
becoming  much  shorter  and  distinctly  fusiform  ;  the  upper  and  low  r 


TSUOA  ,65 

walU  medium,  unequal,  very  dparingly  pitied,  in  the  summer  wood 
lictominK  toniipicuouHly  thicl<cr  and  strongly  pitted;  the  terminal 
wa  Is  coarwiy  pitted,  when  seen  in  plan  like  a  nicve  plate  ;  the  lateral 
wrill*  with  obscurely  Iwrdcred  piut,  1-4.  or  in  the  marginal  cells  and 
low  rays  upwards  of  6,  per  trachcid,  l)ccomin«  reduced  toward  the 
summer  wood,  where  they  are  only  1  or  entirely  wanting.  Bordered 
piu  numerous,  elliptical,  usually  less  than  half  the  trachcid,  in  i  row 
or  o.ten  in  pairs  and  imperfectly  i-rowed.  Fits  on  the  tangential 
walls  of  the  summer  tracheids  not  very  numerous,  rather  small 
Kcsin  cells  and  resinous  tracheids  wanting. 
7dH);eHtial.  Rays  medium  to  high,  sparingly  resinous,  narrow,  strictly 
i-seriate;  the  cells  uniform,  oblong,  rarely  oval. 

U.  TSUOA,  Cakr.     Plates  44  and  45 

Transverse.  (Jrowth  rings  usually  thin,  the  summer  wood  prominent,  usu- 
ally dense.  Resin  passages  rarely  present  (T.  heterophylla)  and 
then  impel  fectly  organized.  Resin  cells  scattering  on  the  outer  face 
of  the  summer  wood  and  distinguished  by  (1)  their  resinous  contents 
(2)  their  .somewhat  advanced  position,  (3)  their  thinner  walls,  and 
(4)  the  sieve-plate  structure  of  the  terminal  walls;  rarely  numerous 
and  zonate  in  the  spring  or  summer  wood.  Resinous  tracheids  wantinir 
(except  in  T.  Mertensiana). 

AWW.  Ray  tracheids  usually  prominent,  .sometimes  interspersed,  usually 
marginal.  Ray  cells  usually  resinous,  more  or  less  contracted  at  the 
ends,  the  terminal  walls  strongly  pitted.  Tracheids  wholly  without 
spirals.  ' 

r.,H};ential.  Fusiform  rays  wholly  wanting.  Ray  cells  rarely  in  pairs,  not 
broad,  chiefly  oval  or  round. 


Synopsis  ok  Species 

Hordered  pits  in  2  rows. 

Resin  passages  wholly  wanting,  the  prominent  resin  cells  scattering 
on  the  outer  face  of  the  summer  wood. 

Pits  on  the  lateral  walls  of  the  ray  cells  2-4,  or  in  the  summer 
wood  1-2,  per  tracheid. 

I.  T.  canadensis. 
Hordered  pits  in  1  row. 

Resin  passages  present  but  imperfectly  formed,  in  more  or  less  con- 
tinuous .series,  the  resin  cells  .scattering  on  the  outer  face  of  the 
summer  wood. 

Pits   on   the  lateral  walls  of   the  ray  cells   1-2,   rarely  3,  per 
tracheid. 

Spring  tracheids  very  large  and  uniform,  distinctly  4-8ided, 
the  walls  thin. 

5.  T.  Merten.siana. 


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266  ANATOMY  OF  THE  OYMNOSPERMS 

Resin  passages  not  present. 

Resin  cells  scattering  on  the  outer  face  of  the  summer  wood. 
Fits  on  the  lateral  walls  of  the  ray  cells  2-4,  or  in  the  sum- 
mer wood  1-2,  per  tracheid ;  the  resin  cells  prominent, 

resinous. 

1.  T.  canadensis. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-2,  rarely  3,  per 
tracheid. 

Spring  tracheids  very  large  and  uniform,  conspicuously 
4-sided,  the  walls  thin. 

5.  T.  Mertensiana. 
Pits  on  the  lateral  walls  of  the  ray  cells  very  variable,  at 
first  5,  soon  uniformly  2,  and  finally  I,  per  tracheid. 
Spring  tracheids  squarish-hexagonal. 

2.  T.  Sieboldii. 

Resin  cells  on  the  outer  face  of  the  summer  wood  and  also  often 
zonate  in  the  spring  or  summer  wood. 
Resinous  tracheids  wanting. 

Pits  on  the  lateral  walls  of  the  ray  cells  2-6,  finally  1, 
per  tracheid. 

3.  T.  caroliniana. 

Resinous  tracheids  in  groups  or  radial  series  in  contact  with 
the  rays. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-4,  chiefly  2, 
and  finally  i,  per  tracheid,  the  orifice  f.nally  becom- 
ing a  prolonged  slit. 

4.  T.  Pattoniana. 


1.  T.  canadensis,  Carr. 
//em/oci 

Transverse.  Growth  rings  thin,  variable.  The  thin  and  dense  .summer 
wood  prominent,  equal  to  about  one  fourth  to  one  half  the  spriiijj 
wood,  from  which  the  transition  is  abrupt.  Spring  wood  very  o|xn, 
the  large  and  very  thin-walled  tracheids  conspicuously  squari.sb,  often 
elongated  radially,  very  uniform  and  in  regular  rows.  Resin  cells 
prominent,  resinous,  not  very  numerous.  Medullary  rays  very  promi- 
nent, somewhat  resinous,  I  cell  wide,  distant  2-10  rows  of  tracheids. 

Radial.  Rays  uniformly  somewhat  resinous  throughout,  the  trach^..as 
often  interspersed.  Ray  cells  somewhat  contracted  at  the  ends,  equal 
to  3-5  spring  tracheids ;  the  upper  and  lower  walls  medium,  unequal, 
very  irregularly  and  often  imperfectly,  sometimes  very  sparingly, 
pitted ;  the  terminal  walls  not  very  strongly  pitted  except  in  the 
summer  wood ;  the  lateral  walls  with  small,  oval  pits,  at  first  with 
a  very  narrow  border,  which  becomes  more  pronounced  toward  the 


TSUGA  267 

summer  wood,  the  lenticular  orifice  hecominj:  oblonjr,  2-4,  or  in  tiie 
summer  wood  1-2,  per  trarheid.  Bordered  pits  round  or  elliptical  in 
1-2  rows,  more  rarely  in  1  row  only,  th.  orifice  large.  Fits  on  the 
tangential  walls  of  the  summer  wood  rather  numerous,  prominent, 
flat.  Resin  cells  IS  ^  wide,  165-240 /i  long 
Tangential  Rays  numerous,  low  to  high,  not  very  broad,  usually  con- 
stricted at  the  position  of  the  frequent  narrow  and  oblong  tracheids  • 
the  parenchyma  cells  rather  equal  and  chiefly  narrowly  oval  to 
oblong,  sometimes  broadly  oval. 

A  tree  21-33  m.  high  and  with  a  trunk  .90-1.15  m.  in  diameter. 

Wood  light,  soft,  not  strong,  brittle,  coarse,  crooked  grained,  difficult  to 

work,  liable  to  wind  shake  and  splinter,  not  durable  (Sargent). 
This  wood  is  of  great  value  for  construction  purposes,  where  it  is  to  be 

constantly  su'>.merged  in  water,  when  it  possesses  elements  of  great 

durability  (Bovey). 

Relative  specific  gravity o  A-yxa 

Percentage  of  ash  residue •     •     •  0^5 

Approximate  relative  fuel  value   ........'        42  20 

Coefficient  of  elasticity  in  kilograms  on  millimeters      '.     '       qoo 
Ultimate  transverse  strength  in  kilograms       ....  307 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  614^ 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  i-iia 

(Sargent)  *  •     •  ■ji4. 

According  to  the  results  obtained  by  Dr.  Bovey  in  the  testing  laboratories 

of  McGill  University,  the  following  data  may  be  given : 
Coefficient  of  strength  in  pounds  per  square  inch  for  : 

5^'"I'"S 5000 

I'"'^'°" 8000 

Compression 

Shear       -^  g^ 

Weight  of  i  cubic  foot 33 

Abundant  on  cold  soils,  Nova  Scotia  and  New  Brunswick,  and  throughout 
Quebec  and  Ontario ;  northward  from  Quebec  to  the  northern  end  of 
Lake  Temiscaming,  thence  to  the  eastern  extremity  of  Lake  Superior  at 
Agawa  (Macoun);  through  the  northern  United  States  to  Newcastle 
County,  Delaware,  and  along  the  Allegheny  Mountains  to  Clear  Creek 
Falls,  Winston  County,  Alabama ;  southeastern  Michigan  and  central 
Wisconsin  (Sargent). 

2.  T.  Sieboldli,  Carr. 

y(//.  =  Tsuga 

Transverse.  Growth  rings  narrow,  uniform,  the  prominent  summer  wood 
dense,  about  one  fourth  to  one  half  the  spring  wood,  from  which  the 
transition    is   gradual.     Spring    tracheids  squarish-hexagonal,   rather 


w 


268 


ANATOMY  OF  THE  GYMNOSPERMS 


If 

r 
[i 


thin-walled,  uniform  in  regular  rows.  Medullary  rays  not  very  numer- 
ous, resinous,  prominent,  and  distant  2-10  rows  of  tracheids.  Kesin 
cells  somewhat  distant  on  the  outer  face  of  the  summer  wood,  but 
readily  recognizable. 

Radial.  Kays  somewhat  resinous  throughout,  the  tracheids  wholly  marginal. 
Kay  cells  chiefly  straight  except  in  the  summer  wood ;  the  upper  and 
lower  walls  medium,  unequal,  strongly  pitted,  especially  in  the  summer 
wood ;  the  terminal  walls  strongly  pitted  ;  the  lateral  walls  with  very 
small,  oval,  bordered  pits  with  a  lenticular  orifice,  which  soon  becomes 
oblong  and  narrow,  at  first  very  variable  and  upwards  of  5,  soon  uni- 
formly 2,  and  in  the  summer  wood  1,  per  tracheid.  Bordered  pits 
numerous,  round  or  elliptical,  in  I  row,  sometimes  in  pairs.  Pits  on 
the  tangential  walls  of  the  summer  wood  rather  numerous  and  flat, 
not  very  large.    Resin  cells  20  ^  wide,  150-275  /i  long. 

Tangential.  Rays  medium,  resinous,  the  cells  unequal,  chiefly  broad  but 
variable,  round  or  oval,  more  rarely  oblong. 


3.  T.  caioliniaiia,  Engel. 
Hemlock 

Trarsverse.  Growth  rings  medium,  variable,  the  dense  and  prominent 
summer  wood  composed  of  rather  small  and  more  or  less  rounded 
tracheids,  the  transition  from  the  spring  wood  rather  abrupt,  often 
quite  gradual,  usually  much  less  than,  or  again  upwards  of  one  half, 
the  spring  wood.  Spring  tracheids  rather  large,  uniform  and  thin- 
walled  in  regular  rows,  usually  elongated  radially.  Medullary  rays 
prominent,  not  very  broad,  I  cell  wide,  distant  2-10  rows  of  tracheids. 
Resin  cells  on  the  outer  fac  of  the  summer  wood  prominent,  resin- 
ous, not  very  numerous,  sometinos  ag/regated  to  form  limited  but 
conspicuous  and  irregular  layers  on  the  mner  face  of  the  summer 
wood. 

Radial.  Rays  uniformly  somewhat  resinous  throughout,  the  tracheids 
prominent,  sometimes  interspersed.  Ray  cells  not  conspicuously  con- 
tracted at  the  ends  except  in  the  summer  wood,  equal  to  6-8  spring 
tracheids,  becoming  much  shorter  in  the  summer  wood ;  the  upper 
and  lower  walls  medium,  very  sparingly  pitted  except  in  the  outer 
summer  wood ;  the  terminal  walls  coarsely  pitted  throughout ;  the 
lateral  walls  with  small,  narrowly  bordered  pits,  the  orifice  at  first 
lenticular,  at  length  narrowly  oblong,  at  first  2-J5,  finally  reduced  to 
I,  per  tracheid  in  the  summer  wood.  Bordered  pits  round  or  elliptical, 
verv  numerous,  usually  as  broad  as  the  tracheid,  in  I  compact  row. 
Pits  on  the  tangential  walls  of  the  summer  tracheids  numerous  but 
small  and  not  very  prominent.  Resin  cells  on  the  outer  face  of  the 
summer  wood  15  ft.  wide,  185-310  /n  long;  those  on  the  inner  face 
very  short  and  cylindrical,  irregular  and  unequal,  and  forming  a  con- 
tinuous series  without  canals. 

Tangential.  Rays  rather  numerous,  medium,  narrow,  resinous,  sometimes 
constricted  by  the  occasional  and  narrow,  oblong  tractieids ;  the  cells 
somewhat  ur  lal,  chiefly  oblong  but  rather  variable,  and  sometimes 
becoming  c 


TSUCIA  269 

A  small  tree  12-15  m.  high,  with  a  trunk  .60-75  tn.  ir  v    .   ,etcr 
Wood  light,  soft,  not  strong,  brittle,  coarse  graine-i. 

Relative  specific  gravity 

Percentage  of  ash  residue    .     . 0-4275 

Approximate  relative  fuel  value  °'*° 

Coefficient  of  elasticity  in  kilograms  on  millimeters      "     '       jf,'' 
U  timate  transverse  strength  in  kilograms  "       ,'1 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms'    64?o 

(s\^?eS)      '"'"^^^^  •     S 

Dry,  rocky  ridges;  rare  and  local  at  elevations  of  4000-5000  feet 
Southern  Allegheny  region;  Bluff   Mountain,   Pinnacle  Mountain    New 
River,  Whitesides  Mountain,  and  Devil's  Court-House  Peak,  North  Caro- 
lina; Saluda  Mountain,  Casar's  Head,  South  Carolina  (Sargent) 


m 


4.  T.  Pattoniana,  S6n6c. 

Mountain  Hemlock.     Patton  Spruce 

Transverse.  Growth  rings  variable,  chiefly  rather  narrow,  the  structure 
usually  open  throughout.  Summer  wood  very  narro^,  rather  ojen 
the  transition  from  the  spring  wood  very  gradual.  Spring  trLheid.! 
rather  large  and  thin-walled,  conspicuously  squarfsh  uniforn,  f' 
regular  rows.  Medullary  rays  numerous,  broad,  ,  eel  wide  ralher 
prominent,  distant  2-7  rows  of  tracheids.  Resin  passageTsonatimes 
present  though  imperfectly  formed,  generally  in  T  .shoft  zone  on  The 

^^Jli^l  °^*"'''y  ^'''^"'  «''°^**'  ""«''•  «^«in  ""«  on  the  outer 
face  of  the  summer  wood  numerous,  resinous,  and  prominent  some 
times  aggregated  to  form  distinct  and  rather  broad  zones.  Res  nous 
the  ra;!'  °""'"^  '"'""  ^'''"P'*  °^  "'"^'  ''"'^^  '"  ^°"«a"  w1"h 

^'^'^naVrJw^'rn^Sn'T'^f"'?''''/.  '■"'"°""'  throughout;  the  rav  tracheids 
!k.,?  '  "l'"^«"'^''  °^'l"  '°""y  wanting.  Ray  cells  straight  or  some- 
what contracted  at  the  ends,  equal  to  10-15  spring  tracheids    The 

,h IT"  rit'^''  '  ?""",«'y  ?'"^^  '  "^'^  "PP'^'-  ^"'l  lower  walls  medium  to 
Si  ^f  ^'Tg'y.Pi't^d,  especially  in  the  summer  wood;  the 
ateral  walls  with  small,  oval,  at  first  narrowly  bordered  pits,  the  len' 
.cular  ontice  at  length  oblong,  .-4,  chiefly  2,  per  tracheid,  becoming 
in  the  summer  wood,  where  the  orifice  is  a  prolongs  '  slit  Bordered 
pits  round  or  elliptical,  chiefly  somewhat  distant  in   ,    row.  Targe 

wnnd'Tf  °"''"  '"■«"•  ^'*''°"  ^"^^  »^"fe^"''^'  walls  of  the  ^umme; 
wood  no  very  numerou.s,  small,  often  remote  and  obscure.  Resin 
cells  on  the  outer  face  of  the  .summer  wood  15-20  u  wide,  1 1  c--'7c  „ 
long,  chiefly  about  150  ^.  Resinous  tracheids  sometimes  locally 
numei.ius,  the  re.sin  ma.ssive.  ^ 

T,w^ential.  Rays  numerou.s,  medium  to  high,  .somewhat  resinou.i ;  the  cells 
obbng-oval,  more  rarely  oval,  rather  equal  and  uniform.  Ray  tra- 
cheids very  few,  terminal,  very  often  wantin-.  ^ 


m 


i 


270  ANATOMY  OF  THE  GYMNOSPERMS 

An  Alpine  tree  rarely  3001.  in  height,  with  a  trunk  1.50-2.10111.  in  diameter. 
Wood  light,  soft,  not  .strong,  close  grained,  satiny,  susceptible  of  a  good 
polish. 

Relative  specific  gravity 0.4454 

Percentage  of  ash  residue 0.44 

Approximate  relative  fuel  value 44-35 

CoeiTicisnt  of  elasticity  in  kilograms  on  millimeters      .     .  775. 

Ultimate  transverse  strength  in  kilograms 307. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  6074. 

Resistance  to  indentation  to  1.37  mm.  in  kilograms     .     .  1664. 
(Sargent) 

Dry  slopes  and  ridges  near  the  limits  of  tree  growth,  from  2700  feet  in 
British  Columbia  to  10,000  feet  in  Colorado. 

Valley  of  the  Fraser  River,  on  Silver  Mountain,  Vale,  and  probably  much 
farther  north  (Macoun);  south  along  the  Ca.scade  Mountains  and  the 
California  Sierras  to  the  headwaters  of  the  ^an  Joaquin  River ;  ca.st- 
ward  along  the  high  mountains  of  northern  Washington  to  the  Caur 
d'Alene  and  Bitter  Root  mountair.s  of  Idaho,  and  the  divide  between 
Thompson  and  Little  Bitter  Root  creeks  in  northern  Montana  (Sargent). 


S.  T.  Mertensiaoa,  Carr. 

lyeslern  Hemlock 

Transverse.  Growth  rings  thin,  the  prominent  summer  wood  dense  and 
about  equal  to  the  spring  wood,  from  which  the  transition  is  gradual. 
Spring  wood  very  open,  the  large  and  thin-walled  tracheids  conspic- 
uously squarish,  in  very  regular  rows,  uniform.  Medullary  rays  vtry 
prominent,  resinous,  rather  broad,  i  cell  wide,  distant  1-9  rows  uf 
tracheids.  Resin  cells  very  prominent  and  resinous,  sometimes  form- 
ing short  rows  of  imperfectly  organized  resin  canals  on  the  outer  face 
of  the  summer  wood. 

Radial.  Rays  uniformly  somewhat  resinous  throughout,  the  tracheids  verj 
unequal,  short,  sometimes  obscure,  not  infrequently  interspersed. 
Ray  cells  narrow,  conspicuously  contracted  at  the  ends,  equal  to  4-9 
spring  tracheids ;  the  upper  and  lower  walls  medium,  unequal,  rather 
strongly  pitted;  the  terminal  walls  coarsely  pitted;  the  lateral  walls 
with  small,  conspicuou.sly  bordered  oval  pits  with  an  oblong  orifice, 
1-2,  rarely  3,  per  tracheid,  becoming  obscure  Mn  the  summer  wowl. 
Bordered  pits  round  or  elliptical  in  i  row.  Pits  on  the  tangenti.il 
walls  of  the  summer  tracheids  numerous  but  small  and  obscure. 
Resin  canals  composed  of  short,  cylindrical  resin  cells,  which  unite 
to  form  disconnected  passages.  Resin  cells  very  long  and  narniH, 
abovit  1 5  fL  wide  and  1 5c  -385  (a.  long. 

Tangent  in  I.  Rays  rather  numerous,  medium  to  high,  resinous,  ratlier 
broad,  the  somewhat  thick-walled  cells  rather  unequal  and  variable, 
round  or  oval. 


YX 


PSEUDOTSUGA  271 

A  large  tree  30-61  m.  high,  with  a  trunk  1.20-3  m-  in  diameter. 
Wood  light,  hard,  not  strong,  rather  close  grained. 

Relative  specific  gravity 05182 

Percentage  of  ash  re.sidue !     !     !     .  o  42 

Approximate  relative  fuel  value .     .  51.61 

Coeflficient  of  elasticity  in  kilograms  on  millimeters     ,     '.  1375. 

Ultimate  tran-sverse  strength  in  kilograms jgg] 

Ultimate  resistance  to  longitudinal  crushing  in  kilogram-  8747. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms     .  1622 
(Sarg.i.t) 

Low,  moist  bottoms  and  rocky  ridges;  very  common  and  reaching  its 
greatest  development  in  western  Oregon  and  Washingtc.i,  often  form- 
ing extensi--  forests  (Sargent);  valley  of  the  Columbia  at  Donald, 
at  1000  feet  elevation,  .hence  westward  to  Stony  Creek  at  3500  feet, 
.hence  the  predominant  tree  to  the  Selkirk  summit  (Macoun);  Alaska, 
thence  south  along  the  islands  and  coast  of  British  Columbia  and 
through  the  Rocky  Mountrns  to  the  Bitter  Root  Mountains  of  Idaho; 
the  western  slopes  of  the  Kocky  Mountains  of  Montr.na ;  through  the 
Cascade  Mountains  of  southern  Oregon  and  the  co:'.:it  ranges  to  Marin 
County,  California,  between  iock  and  4000  fee'  elevation  (Sargent). 

14.  •  PSEUDOTSUGA,  Carr.     Plates  46  and  47 

Transverse.  Growth  rings  and  summer  wood  very  variable.  Resin  pas- 
sages prominent  and  well  formed  without  thylo.ses,  but  with  thick- 
walled  epithelium.  Resin  cells  more  or  less  numerous  on  the  outer 
face  of  the  summer  wood,  not  very  resinous,  and  usually  distinguished 
by  their  (1)  thinner  walls  and  somewhat  advanced  position,  and  (2) 
by  the  sieve-plate  structure  of  the  terminal  walls. 

Radial.  Ray  tracheids  present.  Ray  cells  with  thick  and  coarsely  pitted 
terminal  walls.  Wood  tracheids  always  with  flat  and  close  spirals  in 
double  series. 

Tangential.  Fusiform  rays  present,  generally  narrow,  the  central  tract 
composed  of  i  small  resin  canal  without  thyloses,  but  with  small  and 
thick-walled  ep'-'-elium  cells;  the  ray  cells  thick-walled  throughout. 

Synopsis  of  Species 

Ray  cells  (tangential)  distinctly  oval  or  oblong. 

Pits  on  the  lateral  walls  of  the  ray  cells  small,  round  or  oval,  at  first 
3-7,  soon  1-3,  per  tracheid. 

1 .  *  P.  Douglasii. 

Ray  cells  (tangential)  broad,  distinctly  squari.sh,  more  rarely  oval  or  round. 
Pits  on  the  lateral  wal.s  of  the  ray  cells  conspicuously  larger  than  in 
I,  the  orifice  lenticular,  3-6  per  tracheid. 

2.  P.  macrocarpa. 


■'--TP 


272 


ANATOMY  OF  THE  GYMNOSPERMS 


ft 

i 


Kay  cells  oval  or  round  (tangential). 

Pits  on  the  lateral  walls  of  the  ray  cells  4  per  tracheid. 

3.  ••  P.  miocena. 

1.  *  P.  DougUsii,  Carr. 

Yellow  Fir.     Ortgon  Pint.     Douglat  Fir 

Transverse.  Growth  rings  very  variable,  and  either  very  thin  with  a  close, 
compact  grain,  or  very  broad  with  a  coarse,  open  grain.  Summer 
wood  very  variable,  now  barely  distinguishable,  or  again  upwards  of 
one  half  the  spring  wood,  often  hard  and  flinty ;  transition  from  the 
spring  wood  more  or  les.s  abrupt.  Spring  tracheids  large,  thin-walled, 
hexagonal,  uniform  in  regular  rows.  Medullary  rays  prominent  and 
somewhat  resinous,  rather  few,  i  cell  wide,  distant  2-13  rows  of 
tracheids.  Resin  pa.s.sages  rather  few  and  widely  scattering,  chiefly 
in  the  summer  wood,  the  canal  equal  to  about  i  or  2  tracheids. 
Resin  cells  few  and  distant  on  the  outer  face  of  the  summer  wood, 
not  very  prominent  or  resinous,  chiefly  distinguished  by  their  position 
and  the  sieve-plate  structure  of  the  terminal  walls. 

Radial.  Rays  sparingly  resinous  throughout,  the  tracheids  prominent, 
chiefly  narrow  and  margi  lal,  but  sometimes  interspersed.  Ray  cells 
straight  or  somewhat  contracted  at  the  ends;  the  upper  and  lower 
walls  thickish,  irregularly  and  often  imperfectly  pitted ;  the  terminal 
walls  coarsely  pitted ;  the  lateral  walls  with  small,  elliptical  pits,  the 
border  narrow,  the  orifice  lenticular,  at  first  3-7,  soon  becoming  1-3, 
and  in  the  summer  wood  1,  per  tracheid.  Pits  on  the  tangential 
walls  of  the  summer  tracheids  wanting.  Resin  cells  15-25  \k  wide, 
125-225  /t  long.  Bordered  pits  in  1  row,  sometimes  in  pairs,  gen- 
erally elliptical,  the  orifice  large.  Spirals  generally  wanting  in  the 
summer  tracheids,  the  angle  82°. 

Tangential.  Fusiform  rays  with  linear  and  unequal  terminals.  Ordinary 
rays  low  to  medium,  the  cells  oval  to  oblong.  Medullary  ray  cells  all 
thick-walled. 

This  species  presents  the  most  striking  variationy  of  any  of  the  North 
American  ConiferaE.    These  variati  1.  ns  follows: 

1.  The  growth  rings  occur  in  zone.  aich  there  are  pronounced 
differences  in  the  average  thicknet                     iponent  rings  (52). 

2.  The  growth  rings  vary  from  s-  ..meters  in  thickness  to  less 
than  I  mm.  In  this  respect  a  distinciiou  may  be  made  between  the 
"  fine-grained,"  in  which  the  rings  seldom  exceed  2-2.5  mm.,  usually  beini,' 
much  less,  and  the  "  coarse-grained  "  wood,  in  which  the  rings  approx- 
imate to  4  mm.  in  thickness ;  the  latter  is  further  distinguished  by  its 
coarse,  open  grain,  and  often  very  flinty  summer  wood,  thus  .ipproximat- 
ing  to  the  "  red  fir,"  as  represented  by  the  next  species. 

3.  The  summer  wood  varies  greatly,  either  in  the  same  tree  or  in 
different  trees,  being  in  one  case  barely  if  at  all  distinguishable  ;  nr, 
on  the  other  hand,  becoming  very  prominent,  dark,  dense  and  tliiity, 
and  often  equal  to  the  spring  wood. 


PSEurx)T:Hc;A 


273 


4.  The  size  of  the  trachcid.H  and  the  volume  of  the  lumen  vary  rela- 
lively  to  the  total  area  of  the  cross  section,  whereby  in  some  cases  the 
summer  wood  presents  a  very  dense  structure,  while  in  others  it  is  com- 
paratively open.  The  extreme  variations  observed  in  nine  specimens  from 
different  localiUes  lie  within  the  following  limits : 

Spring  wood     ....  ■,,,,-,  .,     ._ 

Summer  wood       .  ,VJl '^  ~  i)  "  ^^ '^ 

A  large  tree  61-92  m.  high,  with  a  trunk  upwards  of  3.66  m.  in  diameter 
Wood  hard,  strong,  varying  greatly  with  age  and  conditions  of  growth! 

difficult  to  work,  very  durable  (Sargent). 
Two  varieties  are  recognized  :  the  "yellow  fir,"  di.stinguished  by  its  lighter 
color  and  usually  fine  and  compact  grain;  and  the  "red  fir,'  which 
approximates  to  the  characteristics  of  the  next  species  and  is  distin- 
guished  by  its  darker  red  color,  coar.se  grain,  and  flinty  summer  wood 
The  former  is  of  superior  quality  for  constructive  purposes.  The  great 
strength  and  durability  of  this  wood  make  it  the  mo.st  valuable  species 
of  the  Pacific  region,  and  it  is  largely  employed  where  these  qualities, 
joined  to  great  size  of  timber,  are  required. 


Relative  .specific  gravity 

Percentage  of  a.sh  residue   .......     i     .  ' 

Approximate  relative  fuel  value 

Coefficient  of  ela.sticity  in  kilograms  on  millimetcr.s     ! 
Ultimate  transverse  strength  in  kilograms 
Ultimate  resistance  to  longitudinal  cru.shing  in  kilograms 
Resistance  to  indentation  to  1.27  mm.  in  kilograms 
(Sargent) 


05157 
0.08 

5'-53 
1283. 

376. 
8289. 
1608. 


A  comparison  of  these  valu>  ith  those  given  by  Sargent  for  .some  of 
the  more  commonly  u.sed  oak  will  serve  to  show  the  superior  quality 
of  this  timber,  which  has  a  hig.ier  coefficient  of  elasticity  than  our  three 
best  native  species. 


Comparative  Strength  ok  Oaks  and  Pouglas  Fir 
(After  Sargent) 


I'seudotsuga  Uouglasii 
White  oak  (Quercus  alba) 
Ued  oak  ((^uercus  rubra) 
live  oak  (Quercus  virens) 


Coefficient  of 
Elasticity  in  Kil- 
ograms on 
Millitneters 


1283 

97 1 

"37 

113O 


Cltimate  Trans- 
verse StrinKth 
in  Kitogra     > 

370 

3.% 

434 


Ultimate  Resist-  ResisUnce  to 
I  ance  to  I,ongi-  |  Indentation 

tudinal  Crushing  to  1.17  mm.  in 
I    in  Kilograms    i    Kilograms 


8JS9 
S.S3 
.S.7.' 
874S 


1608 
3388 
2825 
5185 


[.W 


ill 


K 


274  ANAIOMY  OK    IIIK  (;VMM)SI'i:kMS 

According;  to  experiments  reported  by  Dr.  Bovey,  as  carried  out  in  the 
teHtitiK  laboratorieR  at  McGill  University  the  following  values  may  be 
ansiKned  to  Douglas  fir  : 

Specially  selected  wood,  free  from  knots  and  cut  out  of  the  log  at  a 
distance  from  the  heart,  gave 

Coefficient  of  bending,  pounds  per  square  inch     .     .  9iOOO 

Coefficient  of  elasticity  in  pounds 2,000,000 

Weight  per  cubic  foot 34 

Ordinary  fiist-quality  wood  gave 

Coefficient  of  bending,  pounds  per  square  inch     .     .  6,000 

Coefficient  of  elasticity  in  pounds 1,430,000 

Weight  per  cubic  foot 34 

The  Douglas  fir  often  forms  extensive  forests  to  the  almost  complete 
exclusion  of  other  species,  ranging  from  sea  level  to  an  elevation  of 
nearly  10,000  feet  in  Colorado,  and  reaching  its  greatest  development 
and  value  in  Oregon  and  Washington  (Sargent). 

All  parts  of  Vancouver  Island  with  the  exception  of  the  exposed  western 
coa.st ;  near  the  49th  parallel  it  ranges  from  the  coast  of  the  mainland 
to  the  Rocky  Mountains,  where  it  occurs  in  a  stunted  form  at  eleva- 
tions of  6000  feet ;  on  the  eastern  slopes  of  the  Rocky  Mountains, 
from  the  49th  parallel  northward  through  the  Porcupine  Hills  to  the 
Bjw  RiviT,  where  it  reaches  its  eastern  extension  at  Calgary;  in 
the  interior  of  southern  British  Columbia  it  is  generally  confined  to 
the  higher  uplands  between  river  valleys ;  northward  it  de.scends  to  the 
general  level  of  the  country  (Macoun);  mountain  ranges  of  Washing- 
ton, Oregon,  and  the  California  coast  ranges  and  the  sierra  Nevadas; 
east  to  Montana,  Wyoming,  Colorado,  and  the  Guadeloupe  Moun- 
tains of  northern  and  eastern  Arizona,  and  '^'uhward  into  Mexico 
(Sargent). 

This  tree  is  known  out  sparingly  in  the  fossil  s.  ,  the  only  representa- 
tive so  far  known  having  been  derived  from  the  glacial  deposits  at 
Mystic  Lake,  near  Bozeman,  Montana.  The  age  of  these  deposits 
cannot  be  accurately  determined  from  the  present  data,  but  they  proi)- 
ably  represent  the  result  of  glaciation  which  may  have  continued  for 
some  time  after  the  period  of  continental  glaciation,  and  even  until 
quite  recently.  The  tree  is,  however,  now  extinct  in  that  locality,  and 
it  is  possible  that  its  elimination  may  have  been  due  to  the  same  general 
cau.ses  that  brought  about  a  withdrawal  of  Sequoia  from  the  prairie 
region  during  glacial  time. 


PSEUDOTSUGA  j^j 

8.  P.  nuKTocarpa,  Mayr. 

Iltmtott 

Trannfene.  Growth  rings  broad,  variable,  the  denM  nummer  wnnrf  ,.«-. 
po^ed  of  rather  nmall.  rounded  tracheidn  in  ir^^^rr  rows  Coward; 
of  one  third  the  spring  wood,  from  which  the  trans  tionii  S.l 
Spring  tracheids  rathe,  ■  irge  and  squarish-hexagonal  thT  Ss 
mediun,  rather  uniform  in  regular  rows.  MedujfarJ  ays  prom 
nent  and  resinous,  numerous  and  wide  chieflv  i  r,Ai  la  ].""" 
.-f.  rows  of  tracheids.  Resin  paTsrKe^numl'sLTT'M ''■""• 
equal  to  al>out  .  tracheid.  Resin'  cellf  n^:ruTand'"p  omSl' 
he  outer  face  o  the  summer  wood,  and  at  once  rtcognTzable  bv 
their  color,  position,  and  structure.  Resinous  trach^iH.  Jf!.  .^  ^ 
P^sent  and  forming  small  group,  or  radTa^^^^Lri^^S.'acTwiVhTh: 

RadiaJ.  Rays  sparingly  resinous  throughout,  the  tracheids  narrow   mar- 
g^nal,  or  some  imes  interspersed.    Ray  cells  straight  or  conUac'ted  i 
theend.s,  equal  to  6-10  spring  tracheids;  the  upper  and  lower  will! 
medium   sparingly  pitted  except  in  the  summer  wood -the  terminal 
wa  Is  chiefly  rather   thin  and  not  very  strongly  pi„ed     the    aTra 
walls  with  prominent  and  re,, nous  pits  conspicuL.r  much  lar Je 
han  in  P.   Douglasii,  the  border  prominent,  Ihe  orifice^"  first  ifn 
ticular   at  length  oblong,  at  first  3-6  throughout  the  spr  nt  wJoS" 

BoX/h'  ^^r^'^^  ''^"•^^''  '"  '  ^'  '"•^'^^■^  ■"  'he  summ"';  wood 
Bordered  pits  numerous  in    i   row,  strongly  elliptical.     Fits  on  the 

ReTn"  S  ""'•"  "f  ••'^''"•""'".j'acheids  f^^^  ver/small  and  obscure' 
Resin  cells  upwards  of  50  ^  wide  and  135-300  ^  long.  Spirals  more 
or  less  obscure,  often  distant,  finally  vestigial  and  in  the  .«uZer 
wood  wanting,  the  angle  70°.  u"i"icr 

Tangential.  Fu.siform  rays  lenticular  or  the  terminals  unequally  linear 
narrow,  the  central  tract  with  ,  small  resin  ,nal.  Ordinar  ra>^ 
sometimes  2-seriate  in   part,  resinous,  broad,  medium  to  high-   the 

or  n.!'„H'"  «"^'  ""T^''  """^  ""'f°'"''  '^q"^"'*'^'  ■^of'^  rarely  oval 
or  round.    Rays  much  more  numerous  than  in  P.  Uougla.xii. 

A  tree  30-54  m.  in  height,  with  a  trunk  of  1.08  m.  in  Hiameter 

Wood  heavy,  hard,  strong,  cross  grained,  very  durab!     difficult  ,■■  work. 

Relative  specific  gravity      .     .  ojt*» 

Percentage  of  ash  residue        ...'.'.".;"  "  008  ' 

Approximate  relative  fuel  value 45  'q 

Coefficient  of  elasticity  in  kilograms  on  millimeters  '.     '.     1050  ' 
Ultimate  tra-'sverse  strength  in  kilograms       ...  361 

Ultimate  resistance  to  longitudinal  crushing  in  kilogams     740c 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  .  164^ 

(Sargent)  "*"■ 

Ury  ridges  and  cafions  between  2500  and  4000  feet  elevation;  the  coast 
ranges  of  California;  San  Bernardino  Mountains  to  the  Ciyamaca 
Mountains  (Sargent). 


f 


^  1  np» 


376 


ANATOMY  OF  THE  GYMN'OSPFRMS 


I 


II 
11 

11 


I.  *  *  P.  mloeMM,  i'enh. 

TVwNJtyM.  Growth  ringt  broad  and  prominent ;  the  tracheidn  of  the  *prini; 
wood  large  and  thin-walled,  the  structure  passinK  ((radually  into  the 
thin  but  rather  prominent  summer  wood  composed  of  about  3-10  rows 
of  thick-walled  trailieid*.  Kesin  cells  net  obvious.  Kesin  passa^eM 
•mall,  not  very  numerous,  chiefly  in  the  summer  wood,  often  double,  as 
in  P.  Douglasii ;  the  epithelium  cells  small  and  thick-wallea.  Medul- 
lary rays  slightly  resinous.  The  entire  structure  of  the  transverse 
section  bears  a  strong  resemblance  to  the  fine-grained  wood  of  P. 
Uouglaaii. 

Radial.  Bordered  pits  in  i  row.  Cells  of  the  medullary  rays  straight,  thu 
thin  upper  and  lower  walls  devoid  of  pits.  Pits  on  the  lateral  walls  of 
the  ray  cells  about  4  per  tracheid. 

TaHgtHtial.  Ordinary  rays  i -seriate  or  2-scriate  in  part,  the  cells  oval  or 
round,  thick-walled,  about  24.5  ^  broad.  Fusiform  rays  narh>w,  the 
cells  thick-walled,  the  resin  canal  narrow. 

Material  silicified  or  preserved  in  the  natural  state. 

Eocene  of  the  Great  Valley    and  Porcupine  Creek  groups,   Saskatche- 
wan ;  Miocene  of  Cariboo,  British  Columbia. 


18.  *  LARDE,  TouRN.    Plates  48  and  49 

Tranmerse.  Summer  wood  prominent,  u.sually  dense,  the  transition  from 
the  spring  wood  more  or  less  abrupt.  Kesin  passages  without  thy- 
loses  but  with  thick-walled  epithelium.  Re-sin  cells  .somewhat  frequent, 
but  scattering  on  the  outer  face  of  the  summer  wood. 

Radial.  Ray  tracheids  prominent,  sometimes  interspensed ;  the  terminal 
walls  of  the  parenchyma  ray  cells  thick  and  strongly  pitted.  Bor- 
dered pits  in  I  or  2  rows.    Tracheids  wholly  without  spirals. 

Tangential.  Fusiform  rays  prominent,  usually  high  and  narrow,  the  cells 
small  and  thick-walled,  the  resin  passage  usually  small.  Cells  of  tlie 
ordinary  rays  oval  to  oblong. 

A  well-defined  genus,  at  once  distinguished  by  the  narrow  and  usually  hJKii 
fusiform  rays,  the  resi  ,  cells  scattering  on  the  outer  face  of  the  summer 
wood,  and  the  absence  of  spiral  tracheids. 


Lt     * 


Synopsis  of  Species 

Bordered  pits  in  1-2  rows. 

Pits  on  the  tangential  walls  of  the  summer  wood  not  confined  to  tiie 
outermost  tracheids. 

Pits  on  the  lateral  wall.-,  of  the  ray  cells  2-6  or  8  per  tracheid. 
Ray  cells  (tangential)  rather  unequal,  .sometimes  in  pairs, 
somewhat  variable,  oval  or  oblong. 
I.   L.  occidentalis. 


I.ARIX 


277 


FilM  on  the  tangenUal  w.ills  ,>(  the  siimmrr  wood  confined  to  ih<; 
outcrrnnttt  traihcid. 

FiU  oti  tliL  lateral  «  il|>.  ,,f  the  ray  ctlU  i-f,  per  tra«  ;uid. 

Ray  celU  (i,,    ,'ential)  equal,   uniform,   and  <  ..lonj,',   more 
rarely  oval. 

2.  •  !..  americana. 
Bordered  pita  In  i  row,  nometimes  In  pairs. 

Fits  on  the  tangential  walls  of  the  summer  »ood  confii.ed  lo  '.r.e 
outermost  tracheid. 

Pits  on  the  lateral  walls  of  the  ray  cells  3-6;  those  on  the  tan- 
((cntial  walls  of  the  summer  wood  numerous  and  small. 

Kay  cells  (tangential)  equal   ai.J  very  uniform,  narrowly 
oblon/r. 

Ivallii. 
Pits  on  the  lateral  walU    '    1.,  ray  cells  2-6  per  tracheid;  those 
on  the  tangential  walls        ine  summer  wood  few,  small,  con- 
fined to  the  outermost  wall. 
Ray  cells  (tangential)  oblong,  more  rarely  oval,  ai.d  much  broader. 
4.   L.  leptolepi.H. 


1.  L.  occidenUUi,  Nutt. 

Tamaraci 

Tratuverse.  Growth  rings  usually  broad,  the  dense  and  prominent  .sum- 
mer wood  about  one  half  the  spring  wood,  from  which  the  transition 
IS  abrupt,  Tracheids  of  the  summer  wood  large,  squari.sh,  in  regular 
rows.  Tracheids  of  the  sprirn,'  wood  very  large  and  thin-walled, 
squarish-hexagonal,  in  very  regular  rows,  rather  uniform.  Medullary 
rays  prominent,  rather  resinous  and  broad,  i  cell  wid-,  distant  2-6 
rows  of  'acheids.  Resin  pas.sages  few,  large,  witho-  thyloses,  the 
epitheh  arrow,  rather  thin-walled,  the  nutritive  layer  thick-walled 

resinous  .esin  cells  widely  scattering  on  the  outer  face  of  the 
,ummer  .v,od,  but  readily  recognized  by  their  abundant  resinous 
confi  nts. 

A'«i.u'.  Kays  conspicuou.sly  resinous  throughout;  the  tracheids  narrow 
!.i.  marginal,  rarely  interspersed.  Ray  cells  chiefly  straight  through- 
'■M'  and  equal  to  3-9  spring  tracheids;  the  upper  and  lower  walls 
chiefly  thick  and  unequal,  sparingly  pitted  throughout,  more  strongly 
so  in  the  summer  wood  ;  the  terminal  walls  coarsely  pitted  throughout ; 
the  lateral  walls  with  elliptical  and  distinctly  bordered  pits,  with  a 
narrow,  chiefly  oblong  or  lenticular  orifice,  numerous,  at  first  6-8  per 
tracheid,  soon  greatly  reduced  in  size,  and  in  the  summer  wood 
abruptly  i  per  tracheid.  Bordered  pits  conspicuously  in  1-2  rows, 
more  rare  y  in  I  row  only,  elliptical,  the  orifice  very  large.  Fits  on 
the  tangential  walls  of  the  summer  wood  rather  numerous  but  small 
and  often  obscure.  Resin  cells  about  12  ?  u  wide  and  60-150  u 
long. 


278  ANATOMY  OF  THE  GYMNOSPKRMS 

Tiuij^eiilial.  Rays  rather  numerous,  low  to  very  high.  Fusiform  rays  with 
a  large  resin  canal  without  thyloses,  the  epithelium  cells  thick-walled. 
Ordinary  rays  often  very  high,  chiefly  very  uniform,  and  not  con- 
tracted at  the  position  of  the  rarely  intersf)ersed  tracheids ;  the  paren- 
chyma cells  rather  unequal,  sometimes  in  pairs,  oval  or  oblong, 
somewhat  variable. 

This  species  appears  to  be  more  or  less  variable  according  to  local  con- 
ditions of  growth.  From  low  elevations  sp>ecimens  appear  to  exhibit 
little  variation,  but  from  high  elevations  (Mt.  Higgins,  Montana,  altitude 
8700  feet)  they  present  very  well-defined  structural  deviations.  These 
■  ppear  chiefly  in  the  much  narrower  and  unequal  growth  rings. 

A    ree  30-45  m.  high,  with  a  trunk  upward  of  1.50  m.  in  diameter. 

Wood  heavy,  exceedingly  hard  and  strong,  rather  coarse  grained,  com- 
pact, satiny,  susceptible  of  a  fine  polish,  very  durable  in  contact  with 
the  soil,  and  of  great  economic  value. 

Relative  specific  gravity 0.7407 

Percentage  of  ash  residue 0.09 

Approximate  relative  fuel  value 74. 

Coefficient  of  elasticity  in  kilograms  on  millimeters     .     .  1658. 

Ultimate  transverse  strength  in  kilograms 524. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  11,023. 

Resistance  10  indentation  to  1.27  mm.  in  kilograms     .     .  2395. 
(Sargent) 

Abundant  in  the  Ki  ■  .tenai-Columbia  valley  of  British  Columbia  (Macoun) ; 
through  the  mountain  ranges  of  northern  Washington  to  the  western 
slopes  of  the  Rocky  Mountains  of  Montana ;  the  Blue  Mountains  of 
Washington  and  Oregon ;  moist  mountain  slopes  and  benches  between 
2500  and  5000  feet  elevation  ;  scattered  among  other  trees,  never  form- 
ing separate  forests  (Sargent). 


2.  L.  americana,  Michx. 

Larch.     Black  Larch.     Tamarack.     Hackmatack 

Transverse.  Growth  rings  rather  broad  and  uniform,  sometimes  double. 
Summer  wood  rather  dense,  about  one  fourth  to  one  half  the  sprini; 
wood,  from  which  the  transition  is  either  gradual  or  abrupt,  the 
tracheids  small,  conspicuously  unequal  and  not  in  very  regular  rows, 
distinctly  rounded.  Spring  tracheids  large,  hexagonal,  radially  eloii 
gated,  thin.  Medullary  rays  prominent,  broad,  1  cell  wide,  distant 
2-8,  rarely  more,  tracheids.  Resin  passages  large,  equal  to  2-3 
tracheids,  devoid  of  thyloses ;  the  epithelium  cells  flat,  rather  thin- 
walled  ;  the  nutritive  parenchyma  scanty,  thick-walled ;  not  very 
numerous,  chiefly  in  the  summer  wood.  Resin  cells  few,  widely  scat- 
tering on  the  outer  face  of  the  summer  wood,  nonresinou.s,  distin- 
guished by  (1)  their  thinner  walls  and  advanced  position,  and  (2)  by 
the  sieve-plate  structure  of  the  terminal  walls. 


LARIX  27^ 

Radial.   Rays  somewhat  resinous  throughout ;   the  trarhcids  np.niin.nf 

con's  .^"Ih:"*^'"^'-  ''--^'^>-^  "y  cclL"statht''o;"  d  : 
uneS  ,nd  ''i^,';"'"'^"  .^^'^^ ;  the  upper  and  lower  walls  thick. 
DittPH^L     K    \      ^  sparingly  pitted;   the  terminal  walls  coarsely 

mo  .  .,"S  =-  T"""'  '"»"•  »PP'"™«'-.  on  "£  ou  e  " 
most   tracneids  only.    The   outer  summer  tracheids   often  show  a 

aruM.rX' '°  "'  '''™^"°"  °^  ^'''^^'^-    «-^<"  ""'-^  M  -^e! 

^''"S£rm^?vs"whhTh•  '"^"'"^high.  sparingly  resinous.    The 
lusiiorm  rajs  with  a  broad  central  tract  and  a  larue  resin  nn-.l 

mo?e  rarefy  oyil  "j^f  «'""^*»'  ':'''^">-  "'h"  equal,  uniform,  oblong. 
nTr"ow"a"d^n7eipeS^r^h:;^s^•  '''"'"^'^'^  ^'  ''^^  ''°'^'''«"  °^  ''^ 

A  tree  24-30  m.  high,  with  a  trunk  upwards  of  .90  m.  in  diameter.  Wood 
heavy,  hard  very  strong,  rather  coarse  grained,  compact,  durable  in 
contact  with  the  soil. 

Relative  specific  gravity 

Percentage  of  ash  residue   ." °-^^36 

Approximate  relative  fuel  value r°^| 

nm^'!'"!***''^''''''y'"''"°Sramsonmillimet'ers     ]     '.  .^g'" 

U  timate  transverse  strength  in  kilograms  ,aj 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  876T 

(Sa"rgeSr                 *°  '"^^  """"  '"  '''Wams^  .     .  .ers! 

Cold  wet  swamps,  often  covering  extensive  areas,  or  northward  on  moist 
uplands  and  intervale  lands.  This  tree,  together  with  the  black  spruce 
dominates  nearly  all  the  swampy  land  from  Newfoundland,  Labrador,  and 
he  eastern  provinces  of  Canada  to  the  Rocky  Mountains;  northward 
to  latitude  6s°,  where  it  is  reduced  to  a  height  of  6-8  feet  (Macoun)- 
southward  through  the  northern  United  States  to  northern  Pennsylvania' 
northern  Indiana,  Illinois,  and  central  Minnesota  (Sargent) 

A  well-defined,  widely  distributed,  and  common  tree  in  the  Plei.stocene 
and  more  recent  deposits,  where  the  remains  are  preserved  in  a  natural 
state,  and  often  most  perfectly. 

Leda  clays,  Montreal;  Scarborough  Heights,  Ontario;  Moo.se  River. 
Ontario;  Lower  Till  of  Fort  Madison.  Iowa;  Ithaca.  New  York;  Don 
valley.  Toronto;  the  black  clays  of  the  Columbian  Formation  (equiva- 
ent  to  Pleistocene  of  northern  localities)  at  Dahlonega.  Georgia;  peat 
bogs  of  New  Brunswick.  s     ,  v  •^^ 


28o 


ANATOMY  OF  THE  GYMNOSPERMS 


% 


3.  L.  LyallU,  Pari. 
Tamaraci.     Mountain  /.iirch 

Transverse.  Growth  rings  narrow,  variable.  The  summer  wood  prominent 
and  dense  or  sometimes  open,  equal  to  about  one  half  to  one  third 
the  spring  wood ;  the  tracheids  in  regular  rows,  very  unequal,  small, 
radially  narrow  and  rounded.  Spring  tracheids  rather  large,  squarish- 
hexagonal,  thin-walled,  very  uniform  in  regular  rows.  Medullary  rays 
prominent,  not  very  broad,  i  cell  wide,  distant  2-8  rows  of  tracheids. 
Resin  canals  not  very  numerous,  small  and  widely  scattering,  devoid 
of  thyloses,  the  epithelium  not  very  narrow,  thick-walled,  Ihe  nutrient 
parenchyma  obscure  or  wanting.  Resin  cells  somewhat  numerous, 
slightly  resinous  and  easily  distinguished. 

Radial.  Rays  sparingly  resinous  throughout,the  tracheids  rather  numerous, 
marginal,  sometimes  interspersed.  Ray  cells  very  stro'--ht  through- 
out, equal  to  3-7  spring  tracheids  ;  the  upper  and  lower  walls  thick, 
somewhat  conspicuously  pitted ;  the  terminal  walls  coarsely  pitted 
throughout ;  the  lateral  walls  with  numerous  small,  oval,  distinctly 
bordered  pits  with  an  oblong,  narrow  orifice,  3-6  per  tracheid,  in  the 
summer  wood  abruptly  reduced  to  I.  Bordered  pits  in  1  row,  often 
in  pairs,  elliptical,  large.  Pits  on  the  tangential  walls  of  the  summer 
wood  rather  numerous  but  small,  and  confined  to  the  outermost 
tracheid  wall.  Resin  cells  few,  15  |4.  wide,  110-155  /i,  chiefly  about 
125  /I,  long. 

Tangential.  Rays  rather  numerous,  low  to  high,  somewhat  resinous.  Fusi- 
form rays  very  narrow  and  variable  in  height;  the  narrow  and  linear 
terminals  often  very  unequal  ;  the  cells  all  thick-walled ;  the  re.sin 
C.I  rial  small,  usually  narrow  and  oblong,  often  much  reduced  and 
nearly  obliterated.  Ordinary  rays  more  or  less  2-seriate  in  part, 
narrow,  the  cells  very  equal  and  uniform,  narrowly  oblong. 

Alow,  straggling,  Alpine  tree,  rarely  exceeding  15  m.  in  height,  with  a 
trunk  upwards  of  1.50  m.  in  diameter. 

In  the  Rocky  Mountains  of  Washington  and  Montana  (Sargent);  summit 
of  South  Kootenai  Pass ;  from  Cascade  Mountain,  Bow  River  Valley, 
westward  ;  forming  the  last  belt  of  timber  on  all  the  peaks  of  the  Rocky 
Mountains,  and  ranging  from  6000  to  7000  feet  elevation  ;  growing  with 
Pinus  albicaulis  (Macoun). 


4.  L.  leptolepis,  Gordon 

Jap.  =  FtijimatsH 

Transversa  Growth  rings  rather  broad.  The  very  prominent  and  dense 
summ  r  wood  composed  of  very  angular  and  unequal  tracheids  in 
irregu.ar  rows ;  nearly  equal  to  the  spring  wood,  from  which  the  tran- 
sition is  abrupt.  Spring  tracheids  large,  thin-walled,  very  uniform  in 
regular  rows.  Medullary  rays  prominent,  I  cell  wide,  distant  2-10  rows 
of  tracheids.  Resin  passages  not  numerous,  somewhat  widely  scat- 
tering, chiefly  in  the  summer  wood,  the  epithelium  rather  thin-walled, 


,3" 


PICEA 


281 


the  nutritive  parenchyma  thick-walled  ;  equal  fo  1-2  tracheids,  devoid 
of  thyloses.  Resin  cells  on  the  outer  face  of  the  summer  wood  few. 
dKslant ;  recosnized  by  their  thin  walls  and  more  advanced  position, 
and  the  sieve-plate  structure  of  the  terminal  walls. 
RadMl.  Rays  somewhat  resinous  throughout,  with  prominent,  chiefly  nar- 
bTJ      II  **  numerous,  marginal    tracheids,   rardy   interspersed. 

walU  r^i  h^^K^'^^^^'i^  •"'"Is*''  throughout;  the  upper  and  lower 
verl  Jrn  I  •»  •/*  1'"*  """^  sparingly,  but  in  the^mmer  wood 
very  strongly,  pitted;  the  terminal  walls  coarsely  pitted  throughout ; 

♦^.^1,  ^'■^«*^"'/'u  '**,''"  ""^alLoval,  bordered  pits,  with  a  lenl 
S  Rnrn''  ==/'.f '"P"y  "-^^duced  to  ,,  per  tracheid  in  the  summer 
wood.  Bordered  pits  very  large,  with  a  large  oval  orifice,  elliptical, 
numerous,  and  often  compact,  two  thirds  the  width  of  the  tracheid 
Ui™"'"fi  ^i'*  ""♦•'«  tangential  walls  of  the  summer  wood  few 
small  confined  to  the  outermost  tracheid  wall.  Resin  cells  i?  a  wide 
1 10-265  /*  long,  chiefly  about  125  ^.  3  f*       *=. 

Tangential.  Rays  rather  numerous  and  resinous.  The  fusiform  ravs 
wtiu J'  ^'^  ""*'  *'"'"'  *'ti!0"t  thyloses,  the  epithelium  rather  thick- 
Ap  ini^rPn  /VT  •T**'"J"  '°  '*'«''•  <=°"tracted  at  the  position  of 
unlfaTnl.  *"•=''*'*•«'  tl"^  parenchyma  cells  chiefly  equal  and 
uniform,  oblong,  more  rarely  oval  and  broader. 


16. 


•PICEA,  Link.    Plates  50  and  51 


Transverse.  Growth  rings  variable,  the  transition  to  the  usually  prominent 
summer  wood  gradual  Resin  passages  with  or  without  thyloses,  but 
wthth.ck-waUed  epithelium  cells.    Resin  cells  wholly  wandng. 

Radial.  Ray  tracheids  conspicuous,  chiefly  narrow,  marginal,  or  some- 

Z^H  '  Trr/'-'.''-  Terminal  walls  of  the  ray  cells  usually  strongly 
pitted.  Tracheids  wholly  without  spirals 
Tangential.  YyxsAiorm  TT^ys  chiefly  narrow,  with  linear  and  often  very 
unequal  and  much-prolonged  terminals;  the  cells  small  and  thick- 
h,f  111  t>.^  central  tract  of  ,  small  resin  passage  without  thyloses 
more  rardy  ova?        ^P"^'^''"'"-    Cells  of  the  ordinary  rays  oblong. 

This  genus  is  readily  distinguished  from  Larix  and  Pseudotsuga  by  the 
absence  of  resin  cells  and  of  spiral  tracheids. 


Synopsis  of  Species 
Ray  cells  (tangential)  variable,  round,  oval,  or  oblong. 

Pits  on  the  tangential  walls  ot  the  summer  wood  chiefly  or  wholly 
confined  to  the  outermost  wall. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-3  per  tracheid. 
Ray  cells  (tangential)  equal. 

Spring  tracheids  rounded-hexagonal,  the  structure  not 
very  open. 

10.   P.  sitchensis. 


282 


ANATOMY  OF  THE  GYMNOSPERMS 


11 3 
if.' 


Pits  on  the  tangential  walls  of  the  summer  wood  few,  often  widely 
scattering;  and  extending  for  some  distance  into  the  summer  wood. 
Pits  on  ihe  lateral  walls  of  the  ray  cells  2-6,  chiefly  4,  per  tr.i- 
cheid. 

Ray  tells  (tangential)  conspicuousl)  unequal. 

Spring  tracheids  large,  thin-walled,  uniform  in  regular 
rows,  squarish-hexagonal. 

6.  P.  polita. 

Ray  cells  (tangential)  usually  very  equal  and  unifor.n,  oblong  or  oval. 
Pits  on  the  tangential  walls  of  the  summer  wood  chiefly  or  wholly 
confined  to  the  outermost  tracheid  wall. 

Pits  on  the  lateral  walls  of  the  ray  cells  2-4  per  tracheid. 

7.  P.  bicolor. 

Pits  on  tht.  lateral  walls  of  the  ray  cells  2-6  per  tracheid. 

3.  •  P.  alba. 

Pits  on  the  tangential  walls  of  the  summer  wood  not  confined  to  the 
outermost  wall,  but  chiefly  small  and  inconspicuous. 
Rays  (radial)  nonresinous. 

Pits  on  the  lateral  walls  of  the  ray  cells  at  first  narrowly  bor- 
dered, 2-5  per  tracheid,  in  the  summer  wood  reduced  to  t. 
Ray  cells  (tangential)  rather  *hick-walled. 

Spring  tracheids  -oundec  -hexagonal ;  the  summer 
wood  rather  open  but  piominent,  upwards  of  one 
half  the  spring  wood. 

4.  P.  Engelmanni. 

Pits  on  the  lateral  walls  of  the  ray  cells  with  an  oblonj; 
orifire,  2-6  per  tracheid,  toward  the  summer  wood  reduced 
to  2,  and  finally  to  I . 

Ray  cells  (tangential)  thin-walled. 

Spring  tracheids  hexagonal,  very  thin-walled ;  the 
summer  wood  very  thin  and  open,  often  barely 
distinguishable. 

8.  P.  pungens. 

Rays  (radial)  locally  resinous,  the  resin  chiefly  confined  to  the 
thicker-walled  and  more  strongly  pitted  cells,  more  rarely  dif- 
fused throughout  the  central  cells. 

Pits  on  the  lateral  walls  of  the  ray  cells  with  a  ienticuiar 
orifice,  at  first  2-6  per  tracheid,  more  rarely  2  throughout, 
in  the  suminer  wood  reduced  to  2,  and  finally  to  i. 

Spring  tracheids  squarish -hexagonal,  not  very  uniform, 
the  walls  rather  thin. 

9.  •  P.  nigra. 


A, 


PICEA 


83 


Pita  on  the  lateral  walls  of  the  ray  cells  with  an  oblon  • 
narrow  orifice,  3-S   per   tracheid,  in  the    summer  wood 
reduced  to  2,  and  Anally  to  1. 
Spring  tracheids  large,  squ?rish-hexagonal.  very  unequal 
in  regular  rows,  the  walls  thin. 

C ,    j*^    i'  aOCFISIS 

Pits  on  the  lateral  walls  of  the  ray  cells  with  a  narrow, 
oblong  orifice,  at  first  sometimes  upwards  of  7  per  tra- 
cheid,  soon  2-4,  and  in  the  summer  wood  1-2. 

Spring  tracheids  large,  squarish,  very  uniform  in  r  gular 
^ows,  the  walls  rather  thin. 
2.  P.  rubra. 
Pits  on   the  lateral  wall,  of  the  ray  cells  with  a  narrow, 
oblong  orifice,  becoming  much  extended  in  the  summer 
wood ;  2-3,  more  rarely  4,  per  tracheid,  becoming  i  in  the 
summer  wood. 

String  tracheids   distinctly   hexagonal,   conspicuously 
unequal  in  regular  rows,  the  wi  Is  not  very  thin. 
'    P.  Breweriana. 

1.  P.  Bre^«reriaiu,  Wats. 
IVeeping  Spruet 
Transverse   Growth  rings  rather  thin  and  uniform.   Summer  wood  rather 
th>n,  of  about  .0-16  tracheids,  prominent,  not  verHen^X  ,„„ 

ri"rrT.  **•'  '""■"«  r'^  «"''"^''  'he  tracheiSs  unequa  Tn 
^fn.H  l^  'T''  "'"''"y  ■"""^'^  compressed.  Spring  tracheids  dii^ 
tinctly  hexagonal,  conspicuously  unequal,  in  regular fows  the  wait 
not  very  thm.  Resin  passages  rather  numer.  ;sfscatter7n;  oft^n  i^ 
small  groups,  and  more  or  less  imperfectly  forced -he  epiSirum 
.n  1-2  rows  of  very  variable  but  thick-walled,  often  resinous  ce^ 
ottracheTds""'  ''™'"""''  '■"'"°"^'  *^'="''  ^-«'  --«=  ^^^^^Cro^. 

^'"*Y;,i^Kr'''t!;!"^'y.'"T°"'''  ^^^  "y  tracheids  marginal.    Ray  cells 
•straight  or  becoming  fusiform  in  the  sumner  wood,  equal  to   6-7 

ireTJllSUfhir""''  r^"^  '^"^^^^'y  pitted,  'the^^upp^r  a'^d' 
ower  walls  rather  thick,  u-iequai,  more  or  less  obscurely  pitted  exceot 

ound   TT\  T*^ '  'u"  '"'"="  ^^''^  ^•«»'  conspicuously  Ordered 
ZZtk^  T    P"^'*'"^  ^"  o>>Iongorilicewhichbecomes  much  ex 

in  tJe'sim^nerToo^^f  V'T^  "^^'^  ^^  ^'  ''^^"^^^^  b*"""""? 
in  "  low  SLT  P-,  '^T^ '  numerous,  often  much  crowded, 
r^.L?    '  ^""P""'-    P"s  on  'i'e  ts  .ial  walls  of  the  summer  wood 

rJ^^al  Tv""""''  ""'  ""^"'"^  '°  "        ^*"'"°'''  tracheid  wall 

lllfi^X  '^^r'^^^^  ^""'"°"«'   "'^'l'"'"   ">  high,  not 

are^Ivnv^f  '  p     ■*""*  chiefly  equal  and  uniform,  oblong,  or  more 

mucLVr^.jingl^d"""""^""'*'"  few.  narrow;  the  termLls  often 


284 


ANATOMY  OF  THE  GYMNOSPERMS 


V 
lit 


A  tree  upwards  of  30  m.,  or  more  rarely  36  m.  in  height,  with  a  trunk 

.60-.90  m.  in  diameter. 
Wood  soft,  close  grained,  compact,  with  a  satiny  surface. 


0.5141 


Relative  specific  gravity 

(Sargent) 

This  tree  oc  ars  m  small,  scattered  groves  in  the  elevated  mountain 
regions  of  California  and  Oregon,  Ltiween  4000  and  7500  feet  altitude 
(Sargent). 

2.  P.  rubra,  Dietr. 
XtJ  Sfruce 

Transverse.  Growth  rings  narrow,  rather  variable.  Summer  wood  narrow, 
not  very  pn.minent,  upwards  of  10  tracheids,  rather  open;  the  tran- 
sition from  the  spring  wood  gradual.  Spring  tracheids  rather  larg  , 
hot  very  thin-walled,  in  very  regular  rows  and  very  uniform,  squari.sh. 
Resin  passages  widely  scattering,  not  numerous,  medium  and  equal 
to  about  2  tracheids  ;  the  epithelium  composed  of  rather  small,  thick- 
walled  cells  ;  wholly  devoid  of  thyloses.  Resin  cells  wholly  wanting. 
Medullary  rays  1  cell  wide,  not  numerou.:,  or  prominent,  distant  3-14 
rows  of  tracheids. 

Radial.  R?>s  sparingly  resinous,  the  resin  usually  localized  and  more  or 
less  confined  to  the  thicker-walled  and  more  strongly  pitted  cells  ;  the 
ray  tracheids  prominent,  marginal,  rarely  interspersed.  Ray  cell.s 
straight  throughout,  or  barely  fusiform  in  the  summer  wood,  equal  to 
about  5-7  spring  tracheids;  the  terminal  walls  strongly  pitted;  the 
upper  and  lower  walls  rather  thin,  distantly  and  obscurely  pitted, 
or  in  the  summer  wood  more  or  less  strongly  pitted  ;  the  lateral  wa!'s 
with  small,  elliptical,  bordered  pits  with  an  oblong  orifice,  at  fir-, 
sometimes  upwards  of  7  per  tracheid,  soon  2-4,  and  in  the  summer 
wood  1-2.  Bordered  pits  broadly  elliptical  or  round,  in  1  row,  not 
crowded,  but  variable  in  size.  Pits  on  the  tangential  walls  t'  the 
summer  wood  very  small  and  much  compressed. 

Tangential.  Rays  somewhat  numerous,  medium,  sparingly  resinous.  Fusi- 
form rays  narrow,  the  resin  canal  small  with  thick-walled  epithelium. 
Ordinary  rays  not  broad,  medium,  the  eel!  very  equal  and  uniform, 
oblong,  or  sometimes  oval  throughout. 

A  tree  usually  21-24  m.,  and  occasionally  30-33  m.  in  hei^'it,  with  a 
trunk  .60-.90  m.  in  diameter. 

Valley  of  the  St.  Lawrence  and  the  northern  shores  of  Prince  Edward 
Island,  southward  through  Quebec,  the  Maritime  Provinces,  and  along 
the  Atlantic  coast  to  southern  Maine  and  Cape  Cod  ;  through  the  hilly 
interior  and  the  mountainous  parts  of  New  England  and  New  York, 
thence  along  the  Allegheny  Mountains  to  the  high  peaks  of  western 
North  Carolina  (Sargent). 


PICKA  285 

3.  •  P.  attM,  Ait. 

Wtrtr  Spruct 
Thtmsvtrte.  Growth  rings  thick.  Summer  wood  thin,  rather  prominent 
f^l'^tf  °"1  ^T^  the  Hpn'ng  wood  from  which  the'^Ston 
is  gradual,  rarely  abrupt ;  the  structure  rather  dense  ;  the  tracheids 
conspicuously  squarish.  Spring  wood  open,  the  tracheids  squarish' 
hexagonal,  uniform  in  very  regular  rows,  the  walls  thin.  Resin  pas- 
sages scattering    rat.ie.   large,  round,  commonly  without    thyloses 

and   .-ather  thm-valled  cells.     Medullary  ray.s  not   very    numerous 
rather  prominent,  narrow.  .  cell  wide,  distant  2-14  rows  of  tracheids 

/ladui/.  Rays  very  daringly  resinous;  the  ray  tr.  cheids  prominent,  mar^ 
ginal.  somet"..es  interspersed  in  the  higher  rays.  Ray  cells  straight 
throughout,  equal  to  5-1 3  .spring  trachHds  ;  the  terminal  walls  coarsdy 
p.t  ed  ;  the  upper  and  lower  walls  rather  thin,  unequal,  sparingly  pitted 
•n  he  spring  wood,  strongly  pitted  in  the  summer  wood  ;  the  lateral 
walls  with  numerous  small,  oval  pits  with  a  lenticular  orifice.  2-6  per 
tracheid,  in  the  summer  wood  abruptly  reduced  to  2,  and  finally  to  1 
Bordered  pits  in  i  row,  numerous,  round.or  elliptical,  the  orifice  large ;  in 
the  summer  wood  becoming  r.  mote  and  finally  obscure,  the  orifice  usu- 
ally  a  prolonged  slit.  Pits  01.  the  tangential  walls  of  the  summer  wood 
very  flat  and  obscure,  chiefly  confined  to  the  outermost  tracheid  wall 

langenttal.  Rays  rather  numerous,  nonresinous,  low  to  hiL'h  Fusiform 
rays  narrow,  the  cells  thin-walled,  the  resin  canal  small,  the  epithelium 
composed  of  thick-walled  cells.  Ordinary  rays  narrow,  not  conspic- 
uously  contracted  by  the  occasionally  interspersed  tracheids  ;  the  cells 
very  equal  ana  uniform,  oblong,  narrow. 

A  tree  15   50  m.  high,  with  a  trunk  upwards  of  .90  m.  in  diameter. 
Wood  light,  soft,  not  strong,  close  and  straight  grained,  compact,  satiny. 

Relative  specific  gravity 040C1 

Percentage  of  ash  residue .  o  12 

Approximate  relative  fuel  value   ........'  40  38 

Coefficient  of  elasticity  in  kilograms  on  millimeters     .'     .'  io'3 

Ultimate  transverse  strength  in  kilograms 3,0 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  5480 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  1117 
(Sargent) 

According  to  Bovey  the  following  data  have  been  obtained  : 
Coefficient  of  strength  in  pounds  for ; 

S*^"*^.'"*: Sooo 

To^s'on 9000 

Compression \^^^ 

Shear .^ 

Weight  of  I  cubic  foot    ...........  30 

N'ewfoundland.  Anticosti,  Nova  Scotia,  and  New  Brunswick,  westward 
through  Quebec  and  Ontario  to  the  forest  limit  of  Manitoba ;  in  the 


i&  I 


386 


ANATOMY  OF  THE  GYMNOSPERMS 


P 

5»r 


prairie  region  being  found  in  the  sand  hills  bordering  the  first  prairie 
steppe.  Occasionally  in  the  valley  of  the  Saskatchewan  and  on  the 
Bow  River  fr:. .  Calgary,  where  it  is  mixed  with  P.  Engelmanni ;  on  the 
Athabasca  to  latitude  54°  7'  34"  (Macoun).  Coast  of  Maine  through 
northeastern  Vermont  and  westward  through  northern  Michigan  and 
Minnesota  to  the  Bla'k  Hills  of  Dakota  ;  along  the  Rocky  Mountains  of 
Montana,  where  it  reaches  its  greatest  development  along  streams  and 
lakes  in  the  Flathead  region,  at  elevations  of  2500-3500  feet  (Sargent). 

Pleistocene  of  the  Scarborough  period  of  which  it  is  characteristic,  at 
Scarborough  Heights,  Ontario. 

Material  preserved  in  the  natural  state,  but  showing  the  efiects  of  exten- 
sive decay. 

4.  P.  EngelBUUiiil,  Engelm. 
IVAiU  Spruct.     Engtlmann's  Spruct 

Tranwerse.  Growth  rings  broad.  Summer  wood  very  prominent  and 
rather  open,  about  one  half  to  one  third  the  spring  wood,  from  which 
the  transition  is  gradual ;  the  tracheids  often  much  compressed  radially. 
Spring  tracheids  rounded-hexagonal,  unequal  in  regular  rows,  the 
walls  thin.  Resin  passages  without  thyloses,  not  very  numerous  ;  the 
epithelium  cells  very  unequal,  rather  thin-walled.  Medullary  rays  not 
very  prominent,  n.«  -row,  i  cell  wide,  distant  2-7  rows  of  tracheids. 

Radial.  Rays  nonresinous;  the  ray  tracheids  prominent,  marginal.  The 
ray  cells  generally  straight  and  equal  to  7  spring  tracheids ;  the  ter- 
minal walls  strongly  pitted  ;  the  upper  and  lower  walls  medium  and 
sparingly  pitted,  except  in  the  summer  wood ;  the  lateral  walls  with 
small,  oval,  and  at  first  narrowly  bordered  pits,  2-5  per  tracheid,  in 
the  summer  wood  gradually  reduced  to  i.  Bordered  pits  in  i  row, 
large,  not  very  numerous,  round  or  elliptical,  the  orifice  finally  becom- 
ing  a  prolonged  slit  upwards  of  34  ;*.  Pits  on  the  tangential  walls  of 
the  summer  wood  small  and  not  prominent,  chiefly  confined  to  the 
outermost  wall. 

Tangential.  Rays  rather  numerous,  medium  to  high,  nonresinous.  The 
fusiform  rays  rather  broad,  the  resin  canal  large  and  round,  with 
thick-walled  epithelium.  The  ordinary  rays  rather  narrow,  the  cells 
very  equal  and  uniform,  narrowly  oblong,  rarely  broader. 

A  large   tree  24-26  m.  high,  with  a  trunk  upwards  of  1.20  m.  in  diameter. 
Wood  very  light,  soft,  not  strong,  very  close  and  straight  grained,  com- 
pact, satiny. 

Relative  specific  gravity 0.3441) 

Percentage  of  ash  residue 0.32 

Approximate  relative  fuel  value 33. 3*5 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  808. 

Ultimate  transverse  strength  in  kilograms 245. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  4271. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms     .     .  5217. 
(Sargent) 


I'ICEA  287 

This  tree  characteriw.H  the  interior  plateau  of  Uritish  Columbia,  with  the 
exception  of  the  dry  southern  portions,  forminx  dense  Krovcs  in  the 
mounuin*.  It  ranges  northward  to  latitude  54^  7-34-  at  an  altitude  of 
2600  feet  (Macoun).  Dry  gravelly  ridges  and  slopes  between  sooo  and 
11,500  feet  elevation,  constituting  the  most  valuable  timl)er  tree  of  the 
central  Rocky  Mountains,  where  it  forms  extensive  forests,  generally 
above  8500  feet  elevation.  Rare  and  of  small  size  in  the  mounuins  of 
Washington,  Oregon,  and  MonUna  (Sargent). 

».  P.  J«soeiisi>,  Carr. 
ya/>.  =  rsAi 

Transi'trse.  Growth  rings  narrow,  uniform.  The  very  thin  summer  wood 
open  and  composed  of  5-10  tracheids.  about  one  fourth  the  spring 
wood,  from  which  the  transition  is  rather  gradual.  Spring  tracheids 
large,  squarish-hexagonal,  thin-walled,  very  unequal  but  in  reirular 
rows.  Resin  passages  not  very  numerous,  chiefly  large,  with  thyloses. 
the  epithelium  of  very  unequal,  rather  thick-walled  cells.  Medullarv 
rays  not  numerous,  rather  resinous  and  prominent,  1  cell  wide  dis- 
tant  2-8  rows  of  tracheids. 

A'afiia/  Rays  sparingly  and  locally  resinous;  the  ray  tracheids  prominent 
and  often  interspersed.  Ray  cells  somewhat  contracted  at  the  ends 
equal  to  3-7  spring  tracheids ;  the  terminal  walls  coarsely  pitted  the 
upper  and  lower  walls  not  very  thick,  conspicuously  pitted,  espcciallv 
in  the  summer  wood  ;  the  lateral  walls  with  small,  oval,  bordered  pits 
with  a  narrow  orifice,  3-5  per  tracheid,  in  the  summer  wood  reduced 
to  2,  and  finally  to  1.  Bordered  pits  large,  strongly  elliptical,  in  1  row 
rather  numerous,  often  in  compact  rows  towards  the  ends  of  tracheids 
Pits  on  the  tangential  walls  of  the  summer  wood  rather  few.  small' 
and  inconspicuous.  '        ' 

Tangential.  Rays  not  very  numerous,  low  to  medium,  sparingly  resinous 
Fusiform  rays  rather  broad,  the  rather  large  resin  canal  with  thick- 
walled  epithelium,  chiefly  without  thyloses.  Ordinary  rays  not  very 
broad,  contracted  at  the  position  of  the  sparingly  interspersed  tra- 
cheids ;  the  cells  rather  thick-walled,  very  equal  and  uniform,  narrowly 
oblong,  rarely  oval.  ' 

6.  P.  poliU,  Carr. 

_/<;/.  =  Iramomi 

Tram'"erse.  Growth  rings  thin,  very  variable.  Summer  wood  prominent 
rather  dense  but  variable,  from  3  tracheids  thick  upwards,  equal  to 
one  half  to  one  third  the  spring  -vood  from  which  the  transition  is 
rather  gradual ;  the  tracheids  variable.  Spring  tracheids  rather  large 
and  thm-walled,  uniform  in  regular  rows.  Resin  passages  rather 
numerous,  large  but  variable,  equal  to  1-4  tracheids,  with  thylo.ses- 
the  epithelium  of  very  unequal,  rather  thin-walled  cells.  Medullary 
rays  rather  numerous  and  broad,  i  cell  wide,  resinous,  distant  2-8  or 
10  rows  of  tracheids. 


^1 


a.  i 


388 


ANATOMY  OF  THE  GYMNOSPERMS 


Radial.  Ray*  locally  very  resinoua  throughout;  the  ray  tracheids  low, 
unequal,  marKinal,  Homctimes  InteraperMd.  Ray  celli  more  or  leu 
contracted  at  the  ends,  eapecially  In  the  Rummer  wood,  equal  to  7-8 
•pring  tracheids;  the  terminal  walls  thin,  often  locally  thickened  or 
sparingly  pitted,  sometimes  entire  ;  the  upper  and  lower  walls  thicker 
and  strongly  pitted  in  the  resinous  cells,  thinner  and  sparingly  pitted 
in  the  nonresinous  cells ;  the  lateral  walls  with  small,  oval,  Dordered 
piu,  the  orilice  narrow,  oblong,  2-6,  chiefly  4,  per  tracheid,  in  the 
summer  wood  rather  abruptly  reduced  to  1.  Borde.ed  pits  numerouH, 
elliptical,  in  1  row,  sometimes  in  pairs.  Fits  on  the  tangential  walls 
of  the  summer  wood  rather  few  and  no;  very  prominent,  flat,  often 
widely  scattering,  and  extending  for  some  distance  into  the  summer 
wood. 

Tanjitntial.  Rays  numerous,  low  to  high,  rather  broad,  resinous.  The 
fusiform  rays  rather  narrow,  with  a  small  resin  canal  and  thick-wallcd 
epithelium.  Ordinary  ravs  contracted  at  the  position  of  the  occa- 
sionally interspersed  and  -ery  narrow  tracheids ;  the  parenchyma 
cells  conspicuously  unequal  and  variable,  from  round  or  oval  to 
oblong,  often  narrow  and  high. 


% 


7.  P.  bicolor,  Mayr. 
Jap.  =  OTShi 

Tranmerst.  Growth  rings  narrow,  uniform.  The  narrow  summer  wood  of 
6-10  tracheids,  about  equai  to  one  third  to  one  half  t1>e  spring  wooti 
from  which  the  tran.sition  is  rather  gradual ;  not  very  dense,  the  tra- 
cheids much  flattened  and  rounded.  Spring  tracheids  conspicuou.sly 
squarish,  thin-walled,  uniform  in  very  regular  rows.  Resin  passages 
rather  large,  often  with  thyloses ;  the  epithelium  composed  of  very 
unequal,  thick-walled  celLs.  Medullary  rays  rather  prominent,  some- 
what resinous,  i  cell  wide,  distant  2-10  rows  of  tracheids. 

Radial.  Rays  somewhat  resinous,  the  resin  localized;  the  ray  tracheid.s 
numerous,  prominent,  and  marginal,  often  interspersed.  Parenchyma 
cells  straight,  equal  to  about  8  tracheids ;  the  terminal  walls  thin,  at 
first  sparingly,  soon  strongly,  pitted  throughout ;  the  upper  and  lower 
walls  medium,  very  sparingly  pitted,  or  again  thicker  and  strongly 
pitted,  especially  in  the  summer  wood ;  the  lateral  walls  with  small, 
elliptical,  bordered  pit.s,  with  an  oblong  orifice,  2-4  per  tracheid, 
abruptly  reduced  to  i  in  the  summer  wood.  Bordered  pits  lar^e, 
elliptical,  or  round,  in  i  row.  Fits  on  the  tangential  walls  of  the 
summer  wood  not  very  numerous,  small,  chiefl>  'onfined  to  the  outer- 
most wall. 

Tangential.  Rays  rather  numerous  but  low  to  medium,  somewhat  resinous. 
The  fusiform  rays  chiefly  low,  narrow,  the  usually  small  resin  canal 
with  thick-walled  epithelium.  Ordinal  '  rays  conspicuously  contracted 
at  the  position  of  the  very  narrow,  interspersed  tracheids;  the  paren- 
chyma cells  thick-walled,  equal  and  chiefly  uniform,  oblong,  often 
narrow,  rarely  oval. 


-;KS ! 


PICEA  ,g^ 

••  P*  pvagMM,  Engeltn. 

Blut  SfriKt.    CcJoraJi)  Sfruet 
Trtuuvtrst.  Growth  x\na%  broad     TK«.  varv  >i.i„       ■    <       .       . 

Kui.hable  summer  w'lod SuaHy  pS.r  .„.  "'.h°'''",  ^"'"'^  !""""• 
.racheid.  very  unc.ual  -Tof.e^ Vu^'"c^4^  ^iV^^^'*  ,7"«' •  .«^^^ 

structure  U  very  open  throuKhout.  Re.in  pajwaires  rather  fc*  .  J^ii 
and  Mattering,  with  .mall  and  very  une.|ual.1hick.wXd  InT.hT  ' 
cell.;  thylow;*  few  or  wanting     MedullJrv  r.!.  L.i  eP'<htlium 

broad   .  Lll  wide,  distant  A'ror;'f  ISh^i:  """'  """"""*  ''"^ 

fol  '"B;;re^'''^'°'*»"^  '^^  »---:i<rruceV  „t3  a:  »;• 

IhL^^  ?  P' V  "V"!""'*' '"  '  '«^. elliptical  or  round;  the  round 
orifir,  becoming  lenticular  in  the  .ummer  wood.  Pits  on  he  tanTn 
tial  walls  of  the  summer  wood  «miii    no.  »  langcn- 

chiefly  confined  to  thTouteZj  ^ani:       '  ""'"''°"''  "  P''""'"''"'' 
TttMgenUal.    Rays  numerous,  nonresinous,  medium  to  hi.rh     Ti,»  r.,  •» 

VT  oX?r' '''  """  ""="  :*'»•"  -all.  Sh'tHck^ailelt^i  M  r 
l^r^AuVXlT  ""♦"•^•^dj,'  the  position  of  the  occa.sion'llly  i^  ! 
spersedtracheids;  the  parenchyma  cells  rather  thin-walled  verveaual 
and  umform,  oblong,  rather  narrow.  vvaueu,  very  equal 

A  tree  30-46  m  high,     ith  a  trunk  upwards  of  .90  m.  in  diameter. 

Wood  very  light,  soft,  weak,  close  grained,  compact,  satiny. 
Ki  lative  specific  gravity  . 

Percentage  of  ash  residue    '.     '. o-374o 

Approximate  relative  fuel  value °'^^ 

fmlS*"/*'^ ''*'•'"''' '"''"^s^'''""' ""'""'meters'  :  :   ?^,-^ 

U  timate  transverse  strength  in  kilograms  .     .  \Z 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms'  ^it 

Resistance  to  mdentation  to  1.27  mm.  in  kUograms  Wti 

(Sargent)                                                                      ■  '• 

Along  borders  of  streams  in  damp  or  wet  soil,  generally  between  6oco  and 
9000  feet  elcvat.on,  and  never  forming  forests.   Rare  and  loc-l.   Valley  of 

»nH  n.'"w«'"""'^'^""*""'°"*^*'  the  mountains  of  Wyoming,  Colorado, 
and  Utah  (Sargent).  * 

9.  *  P.  nigra,  Ait. 
Black  Spruce 
Transi'trse.  Growth  rings  rather  broad,  variable.  The  summer  wood 
usually  much  less  than  but  upwards  of  one  half  the  springTood  Trom 
which  the  transition  is  gradual ;  the  structure  open.  s'prfngUacheW^ 
squansh-hexagonal,  not  very  uniform,  in  regular  rows  the  S 
rather  thm.    Resin  passage,  chiefly  in  the  summer  wo<^  equaf  to  '-4 


I 

[I 
fl 


W. 


290  ANATOMY  OF  THE  GYMNOSPERMS 

IrachcidM  with  ihyloMa ;  the  epithelium  celU  very  much  flatteited, 
rather  thin-walled.  Medullary  ray*  rather  prominent.  1  cell  wide, 
rather  nuineroua,  dintant  J-«  row*  o(  tracheid*. 

Radial.  Kayi  very  sparinKly  rcitinouit;  the  ray  tracheidt  promincnti  mar- 
Kinal,  MmetimeH  inter»j*rr»ed.  Parenchyma  cells  RtraiKht  or  rarely 
narrower  at  the  end*,  long ;  the  terminal  walls  coarsely  pitted ;  the 
upper  and  lower  walls  medium,  sinuatily  unequal,  distantly  and  often 
obscurely  pitted  except  in  the  summer  wood ;  the  lateral  walls  with 
small,  oval,  bordered  pits  with  a  lenticular  oritice,  i-h  per  tracheid, 
more  rarely  2  throughout,  in  the  summer  wood  reduced  to  2,  and 
finally  to  1 .  Bordered  pits  numerous,  crowded,  round,  or  elliptical,  the 
orilice  larxe,  round,  becoming  narrow  in  the  summer  wood  and  par- 
allel with  the  tracheid  axis.  Pits  on  the  tangential  walls  of  the  sum- 
mer wood  very  narrow  and  small,  but  generally  numerous. 

Tanf^tHtial.  Fusiform  rays  very  narrow  and  high  ;  the  cells  small  itsA  thick- 
walled  ;  the  terminals  very  long  and  linear,  often  unequal ;  the  resin 
canal  rather  small  and  narrow,  oblong.  Ordinary  rays  very  narrow, 
the  cells  very  equal  and  uniform,  oblong  and  narrow  at  least  in  the 
higher  rays,  more  rarely  rather  broud  and  oval. 

A  tree  15-21  m.  high,  with  a  trunk  upwards  of  .90  m.  in  diameter. 
Wood  light,  soft,  not  strong,  close  and  straight  grained,  compact,  satiny. 

Relative  .ipecilic  gravity 0-4594 

Percentage  of  ash  residue 0.27 

Approximate  relative  fuel  value 45-71 

Coefficient  of  t\c-  ticity  in  kilogratT><t  on  millimeters     .     .  1100. 

Ultimate  tran.sverse  strength  in  kilograms 318. 

Ultimate  re.'tistance  to  1^  .gitudinal  crushing  in  kilograms  6520. 

Kesistance  to  ir  kntation  to  t.27  mm.  in  kilograms      .     .  1240. 
(Sargent) 

Abundant  in  Newfoundland  and  in  every  part  of  Canada  except  southern 
Ontario  and  the  prairie  region,  ranging  northward  to  latitude  65°,  where 
it  terminates  in  association  <"  th  Betula  papyrifera  (Macoun).  Through 
the  northern  United  State^  >.  Pennsylvania,  central  Michigan,  Wiscon- 
sin, and  Minnesota,  and  alo...;  the  Allegheny  Mountains  to  the  high 
peaks  of  North  Carolina  (Sargent). 

Pleistocene  deposits  at  Hamilton  (Erie  clays),  Ontario ;  the  Moose  River, 
Ontario  ;  Don  Valley  and  the  Leda  Clays,  Montreal.  This  plant  occurs 
in  considerable  abundance  and  is  essentially  typical  of  the  Oon  periwl, 
where  it  is  associated  with  another  unde.scribcd  :«pecies,  possibly  the  samt. 

Material  preserved  in  a  natural  state,  though  usually  much  altered  by 
decay. 

10.  P.  sitchensiB,  Carr. 
Tidttand  Spruct.    Sitka  S/   net 

Transverse.  Growth  rings  thickish.  Summer  wood  very  prominent,  equ.il  to 
or  exceeding  the  spring  wood  from  which  the  transition  is  gradual,  not 
very  dense.    Spring  tracheids  commonly  strongly  rounded-hexagonal, 


PINUS 


25 


thf  walU  rather  thin,  bat  the  Htrurn.r..  ,.  ,  1.  i 
puMKe.  few.  not  viry  UruV  w^^h"  Ll^  '"''l*  ""'  ^'"y  "P*"  «"'" 
thick-walled  cell,.  re.iUf  Medtl  arl  r^vVn  ..'  'P'*'""""'  "'  ■""»"• 
Inent  or  broad,   1   cell  wide    diHUn7I^  ""i '""'""•'"''•P'"'"- 

rarely  11.  °''  '"'"*"'  '"9  row.  0/   tracheidn,  more 

AWm/.    Rays  somewhat   resinous  locallv  •  tk.  „„  .      u    .. 

marginal,  rarely  interspersed  Snch'vm! /iT  tracheids  prominent, 
at  the  ends,  equal  to  6-^0  sbrin„  .«  k  ^J^'  *"■*""  »«"'e*hat  contracted 
pitted;  the  upj^r  and  lowe    w^aK^:^'' =  '^ 

the  resinous  ceHs  and  summer  wo~j T  ""^  "'.'.*"'  ^'"^  *""'«.  or  in 
lateral  wails  with  rathcrTew  and  smaS■;nr;:!^"'r''';  "".^  »""'♦» '  «»"= 
lenticular  orifice.  1-3.  more*  arelvTr-^'r^T^'^'  ^'""^''"^'^  Pi"»  with  a 
reduced  to  2,  and  finalWto  ,  SrfirH  "''^"'' '"  ""  '"""'""  *ood 
.he  orifice  la^Kc  and  rouU  or  SuTar  i n?h  "  '  '"*'  ""P""'' '"«« = 
n«  row  and  parallel  with  the  tracS  aiiT    PU.ZT  T "''  ''^■?'"'"« 

oirmrtrheTiaSr  •"'"•  --  Sy^  rhXsrd't^t 

cells.    Ordinary  rays  rathe   "b^ld    rnl  '"''  'hifk^aHed  epithelium 
position  of  .he\arU  and  S;„X''i'„'r"''^'  T"'"'^'*'*  '»'  'f"*^ 
parenchyma  cells  equal  but  vSlefr„2;  '"'"';P«^'''d  tracheids;  the 
cijudi  out  variable  from  round  to  oval  or  oblong 

Wood  llgM.  .of,,  „„,  ^,,  .1^  .^  .„,^„  ^.^^  ^^^^^  ^^^^^^ 


Relat'  /e  specific  gravity 

Percentage  tf  ash  residue 

Approximate  relative  fuel  value 

fjmm  JrL°^  '''""''"''  '"  kilograms  on  miilimeters "     ' 
U  t  ma  e  transverse  strength  in  kilograms 
Ultimate  resistance  to  loniri'udimi /-I...!,!-     •    1  •.    "     " 
Resistance  to  longitudin.^'crush?*.,  ?.  ?^'"«  '"  .•" K'^a'^"      5653 
(Sarg..nt)  crushing  to  1.27  mm.  in  kilograms  1 160 


0.4287 
0.17 
42.80 
990. 
77. 
5653. 


Cliiefiy  confined  •  .  the  coast  nf  n,:.:  1.  .-  i      ■  . 
cnendin,  more  than  50  mil.s  inland  from  the  coa.s.  (tr^       "' 


17.  •  PINUS,  1 


'<)1:k.\. 


Trans-.  :rse.  Growth   rings  usually  broad     Th,.  m«,  1 

summer  wood  variable     Res  n  n,.  -.  '^  "'  '"'"   Prominent 

prominent  thyloses  and  tHn  writ^rv^r^Tr  "'^^"•'  '^^f^'  '"«^'  ""'^ 

^.     lium.     Resinlcells  wholly  wani^ni''''  '"""'^'•^'  '^'^^eral-layered  epithe- 

.racheid  so  as  to  for^T^ri  ^  !t  ^^Hi^S^S.  ^l^^iti: 


292 


ANATOMY  OF  THE  GYMNOSPERMS 


of  one  or  two  kinds.  Bordered  pits  on  the  tangential  walls  of  the  sum- 
mer wood  either  numerous  (Sec.  I)  or  usually  wanting  (Sec.  II). 
Tracheids  wholly  without  spirals.  Resinous  tracheids  sometimes  pres- 
ent, the  resin  forming  radial  plates  opposite  the  rays  and  simulating 
Sanio's  bands. 
ToHgential.  Fusiform  rays  chiefly  large  and  broad  ;  the  cells  of  the  inflated 
portion  chiefly  large  and  thin-walled:  the  central  tract  occupied  by 
I  large  resin  passage  with  thyloses  and  thin-walled  epithelium.  Ordi- 
nary rays  chiefly  I -seriate,  more  or  less  conspicuously  contracted  by 
the  interspersed  tracheids. 


11 


Synopsis  of  Species 

A.  PINUS  PROPER 

Existing  Species 

Sec.  I.  Pits  on  the  tangential  walls  of  the  summer  wood  prom- 
inent. Medullary  tracheids  prominent,  sparingly  interspersed, 
their  upper  and  lower  walls  not  dentate. 

A.  The  lateral  walls  of  the  ray  cells  (radial)  with  small,  numer- 
ous, and  more  or  less  conspicuously  bordered  pits  ;  the  upper 
and  lower  walls  thick  and  coarsely  pitted  ;  the  terminal  walls 
coarsely  pitted  ;  the  thick  side  walls  (tangential)  not  inflated 
or  incurved.  The  rays  sometimes  show  thin-walled  cells  with- 
out pits,  which  are  conterminous  and  interspersed. 
Ray  cells  (radial)  of  I  kind  only,  all  thick-walled  and  strongly  pitted. 

Rays  nonresinous  (radial),  the  tracheids  numerous,  marginal,  often 
interspersed. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-4,  chiefly  4,  throughout, 
but  finally  2,  per  tracheid  in  the  outer  summer  wood. 

Ray  cell.s  (tangential)  conspicuously  unequal  and  variable, 
from  round  to  oval  or  oblong,  those  of  the  low  rays  often 
three  times  higher  than  wide. 

3.  P.  monophylla. 
Rays  more  or  less  resinous  (radial),  the  tracheids  marginal,  sparingly 
or  rarely  interspersed. 

Pits  on  the  lateral  walls  of  the  ray  cells  2»-4  per  tracheid  throughout. 
Ordinary  rays  (tangential)  sparingly  resinous,  somewhat  con- 
tracted  by   occasionally   inter.sper.sed,  narrowly  oval,  or 
oblong  tracheids ;  the  cells  equal  and  chiefly  uniform,  oval 
to  obiong,  rarely  narrow. 

I.  P.  Parryana. 
Ordinary  rays  (tangential)  somewhat  resinous,  rather  broad, 
not  perceptibly  contracted  by  the  occasionally  interspersed 


PINUS 


293 


and  equal   tracheids ;    the  cells  very  equal,    chiefly   verv 
uniform,  narrowly  oval  or  oblonK.  rarely  broader 
2.  1'.  cembroides. 
Pits  on  the  lateral  walls  of  the  ray  cells  ,-5  throughout,  or  finally 
1-2,  per  tracheid  m  the  summer  wood. 
Ordinary  rays  rather   broad  and   nonresinous   (tangential), 
somewhat  contracted  by  the  narrower  and  smaller,  occasion- 
ally  interspersed  tracheids  ;  the  cells  very  equal  and  uniform, 
narrowly  oval  to  oblong. 

4-  P.  Balfouriana. 

Ray  cells   (radial)  of   2   kinds:    (,)  thick-walled    and    strongly  pitted- 
(2)  th.n-walled,  devoid  of  pits,  conterminous,  and  interspersed 
P.ts  on  the  lateral  walls  of  the  ray  cells  3-6,  soon  4,  or  in  the  outer 
summer  wood  2,  per  tracheid. 

Ordinary  rays  (tangential)  nonresinous,  numerous,  the  cells  equal 
uniform,  oval,  or  oblong.  ^ 

Fusiform  rays  (tangential)  few,  narrow. 

5-  P-  aristata. 

Pits  on  the  lateral  walls  of  the  ray  cells  ,-4  throughout,  or  in  the 
marginal  cells  upwards  of  5  or  6,  per  tracheid. 

Ordinary  rays  (tangential)  numerous,  broad,  the  cells  chiefly  equal 
uniform,  oval,  and  narrow.  '  ' 

Fusiform  rays  (tangential)  rather  numerous,  small,  and  narrow 
6.  P.  edulis. 
B.  Lateral  walls  of  the  ray  cells  (radial)  with  large,  open,  and 
simple,  oval,  or  lenticular  pits,  1-2  per  tracheid;  the  upper 
and  lower  walls  thin  and  distantly  or  even  obscurely  pitted- 
the  terminal  walls  thin  and  entire  or  locally  thickened  ;  the' 
thin  .side  walls  (tangential)  either  inflated  or  incurved 
Ray  cells  (transverse  or  tangential)  with  their  very  thin  side  walls  strongly 
inflated  and  projecting  into  the  cavities  of  the  adjacent  tracheids 

Pits  on  the  lateral  walls  of  the  ray  cells  oval  or  .sc|uarisb,  or  finally 
lenticular,  1-2,  chiefly  i,  per  tracheid  throughout. 

Resin  passages  numerous  and  large,  chiefly  in  or  near  the  summer 
wood ;  when  in  the  former  situation,  central  to  a  large  tract  of 
thin-walled  tracheids. 

10.   P.  reflexa. 
Ray  cells  (transverse  or  tangential)  with  their  thin  side  walls  not  strongly 
inflated,  but  commonly  incurved  or  sometimes  convex. 

Pits  on  the  lateral  walls  of  the  ray  cells  chiefly  1-2  per  tracheid. 
Resinous  tracheids  (radial)  not  present. 

Rays  (tangential)  strongly  resinous,  the  cells  oval,  unequal, 
variable. 


294 


ANATOMY  OF  THE  GYMNOSPERMS 


5 


i^' 


Pits  on  the  lateral  walls  of  the  ray  cells  1-2,  in  the  sum 
mer  wood  reduced  to  I,  per  tracheid. 

8.  F.  monticola. 
Rays  (tangential)  nonresinous. 

Ray  cells  (tangential)  oval,  equal,  and  uniform. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-2,  or  in 
the  marginal  cells  3-4,  per  tracheid. 

9.  P.  flexilis. 

Ray  cells  (tangential),  oblong,  narrow,  equal,and  uniform. 
Pits  on  the  lateral  walls  of  the  ray  cells  1-2  through- 
out, rarely  3,  per  tracheid. 

11.  •  P.  strobus. 

Ray  cells  (tangential)  chiefly  equal,  but  more  or  less  vari- 
able, from  broadly  to  narrowly  oval  or  oblong. 

Pits  on  the  lateral  walls  of  the  ray  cells  2  per  tra- 
cheid throughout,  rarely  i  or  3. 
7.  P.  I  ambertiana. 
Ray  cells  (tangential;  oblong  and  narrow,  more  rarely 
oval  and  broader,  not  very  variable. 

Pits  on  the  lateral  walls  of  the  ray  cells  i  per  tra- 
cheid throughout,  or  in  the  early  spring  wood  2 
per  tracheid. 

12.  P.  parviflora. 

Resinous  tracheids  (radial  or  tangential)  present,  the   resin  in 
plates  opposite  the  rays  and  simulating  Sanio's  bands. 
Rays  (tangential)  nonresinous. 

Ray  cells  (tangential)  oval  or  oblong,  not  very  variable. 
Pits  on  the  lateral  walls  of  the  ray  cells  i  per  tra- 
cheid throughout,  more  rarely  2. 

13.  P.  albicaulis. 

Ray  cells  (tangential)  oblong  and  narrow,  more  rarely 
oval  and  broader,  not  very  variable. 

Pits  on  the  lateral  walls  of  the  ray  cells  1  ptr 
tracheid  throughout,  or  in  the  early  spring  wood 
2  per  tracheid. 

12.  P.  parviflora. 

^SVf .  //.  Pi/s  on  the  tangential  walls  of  the  summer  wood  usu- 
ally wanting.  Medullary  tracheids  prominent,  more  or  less, 
often  strongly,  interspersed,  their  tipper  and  lower  walls  den- 
tate or  the  teeth  so  prolonged  and  united  across  the  cavity  as 
to  form  a  more  or  less  definite  and  sometimes  very  strongly 
defined  reticulum. 


I'lNUS 


295 


chiefly  I,  and  not  exceeding  2,  per  tracheid. 
Ray  cells  of  1  kind  only. 

Epithelium  of  the  resin  passages  resinous. 

Bordered  pits  in  i  row,  sometimes  in  pairs 

Ray  tracheids  simply  dentate,  rarely  interspersed 

Pits  on  the  lateral  walls  of  the  ray  cells  .-2, 'chiefly 
I,  per  tracheid.  ' 

21.  P.  resinosa. 

Ray  tracheids  simply  dentate,  but  numerous  and  inter- 
spersed and  often  predominant. 

Pits  on  the  lateral  walls  of  the  ray  ceils  large,  oval, 
oblong,  or  lenticular.  ,-2,  chiefly  ,,  per  tracheid. 

22.  P.  tropicalis. 
Pits  on  the  lateral  walls  of  the  rav  ppIIc  u,„       j 

dered  in  the  summer  wH  '  '"^'  '"'  conspicuously  bor- 

Epithelium  of  the  resin  pas.sages  nonre.sinous 

Resin  passages  (transverse)  large,  numerous,  scattering. 
Bordered  pits  in  i  row. 

Ray  tracheids  (radial  or  tangential)  simply  dentate 
not  interspersed. 

Pits   on   the  lateral  wall.s  of  the  ray  cells  i 
rarely  2,  per  tracheid. 

23.  P.  Thunbergii. 

Ray  tracheids  (radial  or  tangential)  somewhat  inter- 
spersed, sparingly  reticulated  in  the  summer  wood 
Pits  on  the  lateral  walls  of  the  ray  cells  strictly 
I  per  tracheid. 

24.  P.  densiflora. 

^man  r„d''  ''*T'  ?"'  ""'  '•'^  ">•  «"^  8-"=*%  rather 
Jr^cheid      "^  '  *"'  "''*'''''•  ^'  '"'^'  ^  °'  '"°'«  P" 

Kay  cells  (radial)  of  i  kind  only  and  thin-walled 

Fusiform  rays  (.  ngential)  with  the  cells  of  the  inflated     .nion  aUor 
chiefly  rather  thick-walled.  ^nona^/or 

"""restor  °'  "'  """  '''"'"  (transverse)  chiefly  in  ,-2  rows. 
Summer  wood  dense. 

Bordered  pits  in  i  row,  or  sometimes  in  pairs. 

Pits  on  the  lateral  walls  of  the  lay  cells  1-6  per  tra- 
cheid. 


■iir.>wwfc.a 


,f  ■ 


2Q6 


ANATOMY  OF  THE  GYMNOSPERMS 


s 


Ray     tracheids     strongly     predominant     and 
strongly  reticulated  throughout. 
17.  P.  Banksiana. 
Fusiform  r::iys  (tangential)  with  the  cells  of  the  inflated  portion  a/i  or 
chiefly  thin-walled,  all  broken  out. 

Epithelium  of  the  resin  passages  (transverse)  chiefly  or  wholly  in 
I  row,  nonresinous  (rarely  resinous  in  P.  txda  and  P.  rigida). 
Summer  wood  open. 

Bordered  pits  in  i  row,  sometimes  in  pairs. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-5,  chiefly 
2,  per  tracheid,  becoming  bordered  in  the  summer 
wood. 

Ray  tracheids  sparingly  inters]  lersed,  strongly 
reticulated  throughout. 
15.  P.  rigida. 
Pits  on  the  lateral  walls  of  the  ray  cells  1-4,  rarely  ;, 
per  tracheid. 

Ray  tracheids  more  or  less  reticulated  in  the 
summer  wood,  often  interspersed. 
25.  P.  Murrayana. 
Bordered  pits  in  1-2  rows. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  chiefly 
2-4,  per  tracheid. 
Ray  tracheids  sparingly  (very  rarely  strongly) 
reticulated  throughout. 
39.  P.  taeda,  Linn. 
Pits  on  the  lateral  walls  of  the  ray  cells  i  -5  per  tracheid. 
Ray   tracheids   when    interspersed  very   low, 
strongly  reticulated  throughout. 
14.  P.  clausa. 
Summer  wood  dense. 

Bordered  pits  in  1-2  rows. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  chiefly 
2-4,  per  tracheid. 

Ray  tracheids  sparingly  (rarely  strongly)  retic- 
ulated throughout. 
39.  P.  taeda. 
Ray  tracheids  high,  very  strongly  reticulated 
throughout. 

The  ray  cells  apparently  all  of  i  kind,  but 
differentiating  slightly. 
41.  P.  cubensis. 


PINUS 


297 


Pits  on  the  lateral  walls  of  the  ray  cells  1-5  per  tra- 
cheid. 

Ray  tracheids  strongly  reticulated  throughout, 
often  predominant,  and,  when  interspersed, 
very  low. 

IJ.  J .  clausa. 
Pits  on  th.'  lateral  walls  of  the  ray  cells  1-4  per  ira- 
'.heid. 

Hay  tracheids  chiefly  high,  conspici  ously  pre- 
dominant,  and  strongly  reticulatec  hroughout. 
20.  P.  echinata. 
Bordered  pits  in  1  row,  sometimes  in  pairs. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-4  per 
tracheid. 

Ray  tracheids  chiefly  high,  conspicuously  pre- 
dominant.and  strongly  reticulated  throughout. 
20.  P.  echinata. 
Epithelium  of  the  resin  passages  (transverse)  distinctly  in  1  or 
more  rows,  nonresinous. 

Summer  wood  dense,  rarely  somewhat  open. 
Bordered  pits  in  1-2  rows. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  chiefly 
2-4,  per  tracneid. 

Ray  tracheids  sparingly  (rarely  strongly)  reti-  • 
ulated  throughout. 
39.  P.  tasda. 

Ray  tracheids  high,  very  strongly  reticulated 
throughout. 

Ray  cells   apparently  all  of   i    kind,  but 

differentiating  slightly. 
4'-   P.  cubensis. 
Pits  on  the  lateral  walls  of  the  ray  cells  2-5,  chiefly 
4i  per  tracheid. 

Ray  tracheids  commonly  predominant  and  inter- 
spersed,  very  strongly  reticulated  throughout. 
40.  P.  palustris. 
Epithelium  of  the  resin  passages  (transverse)  distinctly  in  i  or 
more  rows,  resi..  as. 
Summer  wood  open. 

Bordered  pits  in  1  row  or  sometimes  in  pairs. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-4,  rarely  5, 
per  tracheid. 


29^ 


ANATOMY  OF  THE  GYMNOSPERMS 


Ray  trachekls  sparingly  interspersed,  strongly 
reticulated  throughout. 
16.   I',  serotina. 
Pits  on  the  lateral  walls  of  the  ray  cells  1-5,  chiefly 
2,  per  tracheid,  becoming  bordered  in  the  summer 
wood. 

R->y  tracheids  sparingly  interspersed,  strongly 
reticulated  throughout. 
15.  P.  rigida. 
Bordered  pits  in  1  row. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  chiefly 
2  or  3,  per  tracheid,  but  very  variable. 

Ray  tracheids  often  predominant,  interspersed, 
sparingly  leticulated. 
19.  P.  glabra. 
Summer  wood   dense  (sometimes  open  in  P.  txda  and  F. 
cubensis). 

Bordered  pits  in  1-2  rows. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  chiefly 
2-4,  per  tracheid. 

Ray  tracheids  sparingly  (very  rarely  strongly) 
reticulated  throughout. 

39.  P.  ta;da. 

Ray  tracheids  high,  very  strongly  reticulated 
throughout. 

Ray  cells  apparently  all  of  one  kind,  hut 
differentiating  slightly. 
41.  P.  cubensis. 
Pits  on  the  lateral  walls  of  the  ray  cells  2-5,  chiefly 
4,  per  tracheid. 

Ray  tracheids  commonly  predominant  and  inter- 
spersed, very  strongly  reticulated  throughout. 

40.  P.  palustris. 
Bordered  pits  in  1  row. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  chiefly 
2  or  3,  per  tracheid,  but  very  variable. 

Ray  tracheids  interspersed,  often  predominant, 
sparingly  reticulated. 
19.  P.  glabra. 
Bordered  pits  in  i  row,  or  sometimes  in  pairs. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  chiefly 
2-4,  per  tracheid. 


PINUS 


299 


i 


Ray  cells  apparently  all  of  one  kind,  but 

differentiating  slightly. 
41.  F  cubensis. 

»7.  P.  Banksiana. 
Pitson  the  lateral  walls  of  the  ray  cells  ,-4.  rarely  , 
per  tracheid.  ^  "  5' 

Ray  tracheids  sparingly  interspersed,  strongly 

reticulated  throughout.  ^  * 

16.  P.  serotina. 

Pits  on  the  lateral  walls  of  the  ray  cells  ,-5,  chiefly 

^.^J  tracheid.  becoming  bordered  in  J™!' 

Ray  tracheids  sparingly  interspersed,  strongly 
reticulated  throughout.  ^^ 

'5.  P.  rigida. 

D,.      II    ^    J.  .  '^-  ^-  contorta. 

chiefly  thick-walled  '"''^'*'*  P°^'*°n  "^'or 

Summer  wood  dense. 

Bordered  pits  in  ,  row  or  sometimes  in  pairs 

Pits  on  the  lateral  walls  of  the  ray  cells  (.)  .-3 
bordered  ,„  the  summer  wood ;  and  r-)  .-4  cHeflv 
2-3.  per  tracheid.  ^      ^'         ^ 

Ray  tracheids  more  or  less  interspersed,  retic- 
ulated  throughout. 
P   .  .    ,.  34.  P.  pungens. 

Summer  wood  open. 


i>' 


,vj 


•.,» 


.n 


300 


ANATOMY  OF  THE  GYMNOSPERMS 

Bordered  pits  in  i  row  or  sometimes  in  pain. 

Pits  on  the  lateral  walls  of  the  ray  cells  i-j,  chiefly  2, 
per  tracheid,  l)ecoming  bordered  in  the  summer 
wood. 

Kay  tracheids  sparingly  interspersed,  strongly 
reticulated  throughout. 
15.  P.  rigida. 
Pits  on  the  lateral  walls  of  the  ray  cells  (i)  1-4;  and 
(2)  1-3,  chiefly  2,  per  tracheid,  the  two  forms  of 
cells  clearly  defined. 

Kay  tracheids  reticulated  in  the  summer  wood, 
predominant  in  the  low  rays  of  which  they 
often  compose  the  entire  structure. 
36.  P.  muricata. 
Pits  on  the  lateral  walls  of  the  ray  cells  2-4  through- 
out, the  two  forms  of  cells  merging  and  not  always 
clearly  defined. 

Kay  tracheids  strongly  dentate  and  becoming 
sparingly  reticulated   in  the  summer  wood, 
interspersed,  often  predominant. 
30.  P.  chihuahuana. 
Summer  wood  dense. 

Bordered  pits  in  I  row  or  sometimes  in  pairs. 

Pits  on  the  lateral  walls  of  the  ray  cells  2-4  through- 
out, the  two  forms  of  cells  merging  and  not  always 
clearly  differentiated. 

Kay  tracheids  strongly  dentate  and  becoming 
sparingly  reticulated  in  the  summer  wood, 
interspersed,  often  predominant. 
30.  P.  chihuahuana. 
Fusiform  rays  (tangential)  with  the  cells  of  the  inflated  portion  all 
thin-walled  and  usually  broken  out. 

Epithelium  of  the  resin  passages  (transverse)  in  1-2  or  more  rows, 
nonresinous. 

Summer  wood  open. 

Bordered  pits  in  I  row. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  chicHy 
2  or  3,  per  tracheid,  but  very  variable. 

Kay  tracheids  interspersed,  often  predominant, 
sparingly  reticulated. 
19.  P.  glabra. 
Pits  on  the  lateral  walls  of  the  ray  cells  (i)  1-4  ;  and 
(2)  2-4,  chiefly  4,  per  tracheid. 


PINUS 


301 


Ray   trachelds   predominant,  sparingly  retic- 
ulated. 

33-  P-  scopuk  um. 
Bordered  pits  in  1  row,  sometime!!  in  pairs. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-4,  rarely  5 
per  tracheid. 

Ray  iracheids  more  or  less  reticulated  in  the 
summer  wood,  often  interspersed. 
25-  P.  Murrayana. 
Pits  on  the  lateral  walls  of  the  ray  cells  2-5,  chiefly 
3-4.  per  tracheid. 

Ray  tracheids  strongly  predominant,  strongly 
dentate,  and  more  or  less  reticulated  through- 
out. 

31-  P.  Jeflreyi. 
Pits  on  the  lateral  walls  of  the  ray  cells  (i)  1-4. 
and  (2)  >-3.  chiefly  2,  per  tracheid. 

Ray  tracheids  often  predominant,  reticulated 
throughout. 

27.  P.  Coulteri. 
Bordered  pits  in  1-2  rows. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  chiefly 
2-4,  per  tracheid. 
Ray  tracheids  sparingly  (rarely  strongly)  retic- 
ulated throughout. 
39-  P.  ticda. 
Ray  tracheids  high,  very  strongly  reticulated 
throughout. 

41.  P.  cubensis. 
Summer  wood  dense,  more  rarely  somewhat  open. 
Bordered  pits  in  1  row. 

Pits  on  the  lateral  walls  of  the  ray  cells  (1)  1-4; 
and  (2)  2-4,  chiefly  4,  per  tracheid. 

Ray  tracheids  predominant,  sparinglyreticulated. 
33-  P.  scopulorum. 
Bordered  pits  in  I  row,  .sometimes  in  pairs. 

Pits  on  the  lateral  walls  of  the  ray  cells  (1)1-4  ;  and 
(2)  1-3,  chiefly  2,  per  tracheid,  the  two  forms  of 
cells  clearly  defined. 

Ray  tracheids  reticulated  in  the  summer  wood, 
predominant  in  the  low  rays  of  which  they 
often  compose  the  entire  structure. 
36.  P.  muricata. 


*; 


3oa 


ANATOMY  OF  THE  GYMNOSPERMS 


PiU  on  the  lateral  walk  of  the  ray  cell*  (i)  1-3, 
bordered   in    the  •ummcr  wood;   and  (3)  1-4, 
chiefly  3-3,  per  tracheid. 
Ray  tracheids  more  or  leaa  Intenpened,  retic- 
ulated throughout. 

34.  P.  pungent. 
Bordered  pits  in  1-3  rows. 

Pita  on  the  lateral  walls  of  the  ray  cells  3-5,  chiefly 
4,  per  tracheid. 

Ray  tracheids  commonly        '-^minant  and  inter- 
spersed, very  strongly  1  e  .11.    ated  throughou  t . 

40.  P.  palustris. 

Pits  on  the  latei  il  walls  of  the  ray  cells  1-6,  chiefly 
3-4,  per  tracheid. 

Ray  tracheids  high,  very  strongly  reticulated 
throughout. 

41.  P.  cuu<:nsis. 

Epithelium  of  the  resin  passage-^  (transverse)    in  i-3  or  more 
ro'vs,  resinous. 

Summer  wood  dense. 

Bordered  pits  in  i  row. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  chiefly 
3  or  3,  per  tracheid,  but  very  variable. 

Ray  tracheids  interspersed,  often  predominant, 
sparingly  reticulated. 
19.  P.  glabra. 
Pits  on  the  lateral   walls  of  the  ray  cells  2-4  (kt 
tracheid,  rarely  5. 

Kay  tracheids  strongly  reticulated,  often  pre- 
dominant. 

32.  P.  ponderosa. 
Bordered  pits  in  i  row,  sometimes  in  pairs. 

Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  chicriy 
2-4,  per  tracheid. 

Ray  tracheids  sparingly  (rarely  strongly)  retic- 
ulated thr')ughout. 
39.  P.  taeda. 
Pits  on  the  lateral  wMls  of  the  ray  cells  (i)  2-6, 
rhlefl  •  4  ;  and  (2)  1-4,  chiefly  4,  per  tracheid. 
Ray  tracheids  predominant,  very  strongly  ri'tic- 
ulated  throughout. 

35.  P.  inops. 


I'lNlS 


303 


Bordered  pits  in  1-2  rows. 

Pits  on  the  lateral  wall*  of  the  ray  itlln  1-^,,  chiefly 
2-4,  per  trachcid. 
Ray  tracheidH  hi^h,  very  iitronj{ly  reticulated 
throughout. 

41-   •'.  cubensis. 
Pits  on  the  lateral  walls  of  the  ray  cells  2-5,  chiefly 
4)  l)cr  tracheid. 

Kay  trachcids  sparingly  interspersed,  predomi- 
nant, strongly  dentate,  and  .somewhat  retic- 
ulated in  the  summer  wood. 
38.  I'.  Sabiniana. 
Ray  tracheids  commonly  predominant,  often 
interspersed  and  very  strongly  reticulated 
throughout. 

40.  F.  palastris. 
Pits  on  the  lateral  walls  of  the  ray  cells  1-6,  thitfly 
4i  |>er  tracheid. 

Ray  tracheids  sparingly  (rarely  strongly)  retic- 
ulated throu-'hout. 
39.  P.  taida. 
Summer  wood  open. 

Bordered  pits  in  1  row  or  .sometimes  in  pairs,  the  latter 
sometimes  numerous  (P.  arizonica). 

Pita  on   the  lateral  walls  of  the  ray  cells  (1)  i-j, 
rarely  6,  chiefly  2  ;  and  (2)  1-3  per  tracheid. 
Tracheids  sparingly  predominant  and  sparingly 
reticulated. 

37-   P.  insignis. 
Pits  on  the  lateral  walls  of  the  ray  cells  (1)2-4; 
and  (2)  2-3  per  tracheid. 

Ray    trachcids     strongly     predominant     and 
strongly  reticulated. 
29.   P.  Torreyana. 
Pits  on  the  lateral  walls  of  the  ray  cell.s  2-4  per 
tracheid. 

Kay  tracheids  dentate  and  .somewhat  reticulated 
throughout,  sometimes  interspersed  and  pre- 
dominant. 

28.   I*.  tul)erculata. 
Pits  on  the  lateral  walls  of  the  ray  cills  2-4,  chietiy 
4.  per  tracheid. 


304  ANAIX)MY  OF  THE  (lYMNOSPERMS 

Ray  trachcidn  itironKly  predominant,  utronKly 
dentate,  and  tomcwhat  reticulated  In  the 
Mummcr  wood. 

26.  v.  arixonica. 
PitH  on  the  lateral  witllK  of  the  ray  cells  (1)  i-(>, 
chiefly  4 ;  and  (2)  1-4,  chiefly  4,  per  tracheid. 
Kay  tracheidH  predominant,  very  strongly  retit 
ulated  throughout. 
35.  v.  inops. 
Bordered  pits  In  1  row. 

PitH  on  the  lateral  walU  of  the  ray  cells  1-6,  chiefly 
2  or  3,  per  tracheid,  but  very  variable. 

Kay  tracheids  often  predominant,  interspersed, 
sparingly  reticulated. 
19.  P.  glabra. 


B.    ••PITYOXYLON  (Pinoxylon) 

F.xlinct  Species 
Kay  tracheids  present. 

Upper  and  lower  wall.s  of  the  ray  tracheids  dentate. 

Bordered  pits  in  2  rows. 

Kesin  passages  numerou.s,  large,  scattering.     • 

Pits  on  the  lateral  walls  of  the  ray  cells  1-2  per  tracheid. 

42.  ••  1'.  (Pinoxylon)  dacotense. 
Upper  and  lower  walls  of  the  ray  tracheids  not  dentate. 

Bordered  pits  in  i  row. 

Transition  from  the  spring  to  the  summer  wood  gradual. 
Or(iii..-iry  rays  (tanijential)  1-2  .seriate  in  part. 
Kcsin  passages  (tran.sverse)  very  large. 

Medullary  rays  (transverse)  distant  3-8,  more 
rarely  8,  rows  of  tracheids. 

43.  ••  P.  Aldersopi. 
Ordinary  rays  (tangential)  strictly  1 -seriate. 

Kesin  passages  (transverse)  very  large. 

Medullary  rays  (traasverse)  distant  upwards  of 
25  rows  of  tracheids. 

44.  *  •  P.  amethy.stinum. 

Resin  passages  (transverse)  r.ither  large,  the  r|ii- 
thflial  cells  resinous. 

Medullary  rays  (transverse)  distant  upwanU  uf 
9,  or  rarely  1  5,  rows  of  tracheids. 

45.  ••P.  (Pinus)  Columbiana. 


IMNUS 


305 


Rc»ln  p»»imgt»  obliterated. 

Bordered  pim  on  the  lateral  wall*  of  the  ray 
celU  a-3  per  trachcid. 
4fi    ••  I'.  J'eaii. 
Bordered  pit.  in  1-3.  chiefly  2,  row.,,  round  or  hexagonal. 
Ordinary  rays  (tsnKenfial)  2-iieriate  in  part. 
Renin  pansageii  not  rcprewnted. 

Kay  tracheid*  wholly  wanting.      ^^'  '  *  '"    ''''•^"•*- 
Bordered  pits  in  1  row. 

Resin  pas»aKe»  numerous,  large,  chiefly  in  the  summer  wood. 

filled   with  prominent   and   resinou.    thylose..   the  epiihelium 

1-2  celb  thick,  not  extended  into  parenchymatous  tracts. 

4H.  •  •  I',  .statcnen.se. 

Resin  passages  numerous,  small,  chiefly  in  the  summer  wood,  devoid 

of  thylo.sPs,  the  epithelium  composed  of  a  single  layer  which  ex- 

tendsintoaprominentandoften  broad  tract  of  wood  parenchyma. 
49-  ••P.  scituatensc. 


A.  PINUS  PROPER 
Existing  Species 

Section  /.    Soft  Pines 

1.  P.  Parryaiu,  Engclm. 
Pineit.    Nut  Pine 
Transverse.  Growth  rings  chiefly  narrow  but  very  variable    Summer  u,~^ 
very  open  and  chiefl>  ver/thin,  but  in  the   Cader  Hnrujwa^ 
of  one  half  the  spring  wood,  from  which  the  transition  is  ven  gradual 
the  trache,ds  in   regular  rows,  con.spicuou.sly  unequal  Tnd  founded 
Spring  trachedssquarish-hexagonal,  unequal  in  regular  rows  the  vJlfs 
rather  thin.    Medullary  rays  numerou.s,  broad,  1  cell  wide  d  stan,  ,  a 
rows  of  trachelds.     Resin  pas-sages  numerous,  med  urn   and  variable 
very  scattering  throughout  the  entire  growth  ring;  the  ;es eral  fa  ered 
epithelium  composed  of  very  large,  rather  thick^^alled  cells  Ze  or 

Radial.  Rays  sparingly  resinoas;  the  tracheids  numerou.s,  marginal,  hith 

a'oVtu^TnTht-    P='--'^>"'=^  ->•  ""^  ^•'''=">-  "t^iKHt^nd  VS 
\T.^1-        u  narrower  growth  rings  and  in  the  summer  wood 

thick  and  conspicuously  though  often  distantly  pitted,  becoming  more 
strongly  pi„ed  in  the  fusiform  cells;  the  terminal  walls  localK  ,h  ck 
ened  or  co.  ely  pitted  ;  the  lateral  walls  with  small,  round  pits  w  th 
a  more  or  less  definite  though  variable  border  and  a  lenticular  orifice 
—4  per  tracheid.    Bordered  pits  in  1  row,  rather  numerou.s,  broadly 


ii 

BiJ 


306  ANATOMV  OF    I'HE  (IVMNOSPKRMS 

elliptical.  Pits  on  the  tangential  walls  of  the  summer  wood  rather 
numerous,  small  and  chiefly  confined  to  the  two  outermost  walls.  Resin- 
ous tracheids  wanting. 
Tangential.  Fusiform  rays  numerous,  very  narrow  ;  the  cells  of  the  inflated 
portion  all  thin-walled  and  usually  much  broken  out ;  the  .somewli.it 
thicker-walled  structure  of  the  central  tract  generally  present  and 
embracing  a  small  resin  canal.  Ordinary  rays  sparingly  resinous, 
medium,  numerous,  broad,  somewhat  contracted  by  occasionallv  ,',cr. 
-spersed,  narrowly  oval  or  oblong  tracheids;  the  thick-w  l?j,l  c.ilv 
usually  equal  and  .somewhat  uniform,  oval  to  oblong,  rap  y  narrow. 
Resinous  tracheids  wanting. 

A  small  tree  6-9  m.  high,  with  a  trunk  upwards  of  .45  m.  in  diai     'c- 
VVood  light,  soft,  close  grained,  and  compact. 

Relative  specific  gravity       0.5675 

Percentage  of  ash  residue 0.54 

Approximate  relative  fuel  value 56.44 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  378. 

Ultimate  transverse  strength  in  kilograms 182. 

Ultimate  resistance  to  cru.shing  in  kilograms       ....  5420. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  3126. 
(Sargent) 

Larkin's  Station,  San  Diego  County,  California,  and  southward  info  Lower 
California,  where  it  forms  extensive  forests  on  high  mesas  and  slopes 
(Sargent). 

2.  P.  cembroides,  Zucc. 

Piiion.    Xiit  Pine 

Traiisi'crse.  Growth  rings  not  broad,  variable,  more  or  less  conspicuously 
double,  the  structure  as  a  whole  rather  den.se.  Summer  wood  rather 
open,  either  very  thin  or  upwards  of  equal  to  the  spring  wood,  from 
which  the  transition  is  very  gradual  and  from  which  it  cannot  he 
readily  distinguished;  the  tracliiids  distinctly  rounded,  unequal,  but  in 
rather  regular  rows.  Spring  tracheids  hexagonal,  not  large,  very  un- 
equal and  variable,  but  in  regular  rows.  Medullai  v  rays  prominent 
and  numerous,  broad,  i  cell  wide,  distant  i-6,  rarely  10',  rows  of  tra- 
cheids. Resin  passages  numerous,  not  large,  chiefly  in  the  middle  or 
inner  portion  of  the  growth  ring,  the  several-layered  epithelium  com- 
posed  of  large,  thick-  and  thin-walled,  nonresinous  cells. 

Radial.  Rays  somewhat  resinous,  the  resin  localized,  granular,  rarely  mas- 
sive ;  the  tracheids  not  very  numerous,  marginal,  rarely  interspersed  ; 
the  lateral  walls  with  very  small  pits  about  2  per  tra'cheid.  Paitii- 
chyma  ray  cells  conspicuously  contracted  at  the  ends  throughoul, 
.short,  equal  to  8-10  tracheids;  the  upper  and  lower  walls  thick,  iini 
form,  conspicuou.sly  pitted  throughout  ;  the  terminal  walls  thin  bnl 
locally  thickened  or  more  often  coarsely  pitted  ;  the  lateral  walls  \\\\\\ 
small,  round  pits,  with  a  more  or  less  obvious  though  very  une(|u.il 
border  and  a  lenticular  orifice,  at  first  2-4,  but  in  the  summer  woi'd 


PINUS 


307 


^^'Ttll  ^'3.'Vo  K2^!:^i^'  ""tTT'-  ''■' '" ' 

numerous.    Pits  on  the  tanc^nt^l  vvalU  nf  !l"^   '"'"'  '"   '  '■°«' 
and  numerous,  extending  yfrinfn  1  *^^  '""1"'"  "■°"''  ^"'^» 

cheids  wanting  ""'""'*'"«  '^"^  '"'"  ">«  summer  wood.     Ke.sinous  tra- 

the  persistent,   thicker Vali^d'tn^ra    ,'a  ^   wtch^in^duH"^'  ""^! 
broLel-.    Res;2s\7c:elTa'nu"nl""""'^°^^'°'-°'^'°"^'  --'^ 


A  small  tree  6-7  m.  high,  with  a  trunk  rarely  exceeding  .30 
Wood  light,  soft,  very  close  grained,  and  compact. 


m.  in  diameter. 


Specific  gravity 

Percentage  of  ash  residue °*^5i2 

(Sargent)  °-9° 


Dry  ridges  and  slopes  at  3500  feet  el 


Arizona  and  through  northern  Mexico  (Sargent). 


evation.    Santa  Catalina  Mountains  of 


a] 


fIS  1 


3.  p.  monophylla,  Torr. 
Pittflit.    A'ut  Pine 

A<7>fm/.  Rays  non res, nous ;  the  tracheids  numerou.s,  mar-inal   often  int.r 

ZTJ-  ■  '^r'^^^y^''  '"''-  ""■^^'^°^''  «'™"«'y  con  racLd  a,  the  end' 
the  terminal  walls  commonly  thick  and  coarselv  nit.^ri      hi  J 

ower  walls  thick  and  strongly  pitter,h?h  eral  Sk  w'th''''"  '"'^ 

ess  obviously-border^d  pits^  'wfth  a  prlngJd  s  i,  liie  orifice  whic°h 

cheTfn  ir'^t^  !r  "^  '''''"  'P''^^  "--'  --rchiefl;  4  per  .a 
che^d,  final  y  reduced  to  2  in  the  outer  summer  wood.  Bordered  ns 
numerous,  ,n  ,  row,  dliptical.    Pits  on  the  tangential  waifs  of  the  sum 

rousTr^^h-eidTrtinT'""'"  '"  '-'''  -"-^''''--^  '-«'-!-    'Z- 

^""■fn'JZ^A  ^'"■1-^°''",'  '■"^''  ""'"  """-erous  and  narrow,  the  cells  of  the 
nrtated  portion  large  and  very  thin-walled,  often  much  broken  ou  he 
pemsten,  central  tract  containing  a  resin  canal  of  n,edium  s  ze     Ord 

SSL"d 'trrh^d'^fh  •  ''"W'  ■'"^"^'"«'>'  ^'^'^'"°"^'  -  contacted  '; 
interspersed  trache.ds ;  the  cells  conspicuou.sly  unequal  and  variable! 


_hsM    -i 

e 


308  ANATOMY  OF  THE  GYMNOSPERMS 

from  round  to  oval  or  oblong,  those  of  the  low  rays  often  three  times 
higher  than  wide,  those  of  the  higher  rays  sometimes  twice  the  width 
of  others. 

A  small,  bushy  tree  4-6  m.  high,  with  a  trunk  upwards  of  i  m.  in  diameter. 
Wood  light,  soft,  weak,  brittle,  close  grained,  and  compact. 

Specific  gravity 0.5658 

Percentage  of  ash  residue 0.68 

Approximate  relative  fuel  value 56.20 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  435. 

Ultimate  transverse  strength  in  kilograms       123. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  4389. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  2713. 
(Sargent) 

Dry  gravelly  slopes  and  mesas  between  3000  and  6000  feet  elevation.  Near 
Lake  Utah,  to  the  eastern  foothills  of  the  California  Sierras,  and  south 
along  the  mountain  ranges  of  the  Great  Basin  to  the  San  Francisco 
Mountains  of  eastern  Arizona  (Sargent). 


4.   P.  Balfouriana,  A.  Murr. 
Foxtail  Pine 

Trans'jerse.  Growth  rings  narrow,  uniform,  the  structure  very  open  through- 
out. Summer  wood  thin,  of  2-6  tracheids  and  open,  the  tracheids 
large  in  regular  rows,  uniform,  the  transition  from  the  spring  wood 
gradual.  Spring  tracheids  rather  large,  very  thin-walled,  hexagonal, 
chiefly  in  regular  rows,  but  conspicuously  unequal.  Medullary  rays 
rather  prominent  and  numerous,  broad,  i  cell  wide,  distant  2-8  rows  of 
tracheids.  Resin  passages  medium,  rather  numerous,  widp'y  scatter- 
ing, the  somewhat  extensive  epithelium  composed  of  1."  n-walled, 
more  or  less  resinous  cells. 

Radial.  Rays  sparingly  resinous  ;  the  tracheids  rather  numt.    .  rginal, 

rarely  interspersed.  Parenchyma  ray  cells  short  and  sirai^  i ;  the  upper 
and  lower  walls  thick  and  very  strongly  pitted  ;  the  lateral  walls  with 
numerous,  small,  round,  or  oval  pits,  at  first  with  a  prominent  bordtr 
and  narrowly  lenticular,  prolonged  orifice,  the  border  becoming  obscure 
and  variable  toward  the  summer  wood,  and  the  orifice  broader,  1-5  per 
tracheid,  finally  reduced  to  1-2  in  the  summer  wood.  Bordered  pits 
numerous  and  round,  in  1  row,  nearly  as  broad  as  the  tracheid.  Pits  on 
the  tangential  walls  of  the  summer  wood  very  numerous  and  contig- 
uous on  the  outermost  wall,  becoming  scattering  in  the  older  tracheids, 
small  but  rather  broadly  lenticular.    Resinous  tracheids  wanting. 

Tangential.  Fusiform  rays  narrow,  the  cells  of  the  inflated  portion  larijc, 
thin-walled,  resinous,  the  resi-  ^.assage  not  large.  Ordinary  rays 
medium  to  high,  rather  broad,  ■  onresinou.s,  and  somewhat  contracted 
by  the  rather  narrower,  smaller,  and  occasionally  interspersed  tra 
cheids ;  the  thick-walled  cells  very  equal  and  uniform,  narrowly  oval  to 
oblong. 


PINUS  30^ 

A  small  tree  15-19  m.  hiKh,  with  a  trunk  upwards  of  .90  m.  in  diameter 
Wood  I.Kht,  soft,  weak,  brittle,  very  close  Rrained,  compact,  satiny,  and 
susceptible  of  a  good  polish. 

Specific  gravity 

Percentage  of  ash  residue     .     .     .     .     " o'lV^ 

Approximate  relative  fuel  value     .     .  , .  1 7 

Coefficient  of  elasticity  in  kilograms  on  millimeters  ■     '  ciu 

Ultimate  transverse  strength  in  kilograms  ,«, 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  ^qs' 

Resistance  to  indentation  to  1 .27  mm.  in  kilogrpms  2^50' 

(Sargent)  ^^ 

Dry,  open  ridges,  forming  upon  Scott's  Mountain  a  broad  belt  of  open 
forest  between  5000  and  8000  feet  elevation.  Mt.  Whitney,  California 
and  about  the  head  waters  of  the  King  and  Kern  rivers  (Sargent) 


5.   P.  aristata,  Engelm. 

Foxtail  Pine.     Hickory  Pine 

Transverse.  Summer  wood  thin,  upwards  of  8  tracheids,  barely  distinguish- 
able,  very  open,  the  tracheids  often  variable  in  more  or  less  conspic- 
uously irregular  rows.  Spring  tracheids  rather  large,  conspicuously 
squari-sh-hexagonal,  very  uniform  in  regular  rows,  the  walls  thin  the 
transition  to  the  summer  wood  very  gradual.    Medullary  rays  rather 

KL'      k'^  •'''■""''■  '  ""  ^'^'^  '"^*^"*  ^-*'  -""^-^  r-^^'y  .o^ows  of 
tracheids.    Resm  pa.ssages  numerous,  rather  large,  the  rather  exten- 

non're'sinousTeJr"''  '''''''""'"  ^°'"P°^^'^  ^'  '^'«^^'  ^'^  *^--^"^d. 
Radial.  Rays  sparingly  resinous  throughout;  the  tracheids  numerous,  mar- 
ginal, sparing  y  interspersed.  Parenchyma  ray  cells  of  2  kinds  •  (  )  the 
cells  more  or  less  strongly  contracted  at  the  ends  ;  the  upper  and  lower 
walls  thick,  strongly  pitted;  the  terminal  walls  coarsely  pitted  "  the 
lateral  walls  with  round  or  oval  but  rather  small  pits,  with  T lenticular 
orifice  and  an  obvious  border  which  becomes  variable  and  obscure 
toward  the  summer  wood,  at  first  3-6,  soon  uniformly  about  4,  or  in 

hL^s^h''  ^TfJ  ""'"^  '•  P""  '''"'^^''^  !  ■■»"d  <2)  "">*  occasionally 
nterspersed  and  oftt.;  conterminous  with  the  cells  of  the  first  kind; 
the  terminal  walls  thin  and  not  pitted,  but  often  locally  thickened 
the  upper  and  lower  walls  thin  and  not  pitted ;  the  lateral  walls  devoid 
VJT.A  ^%T  P'^^  numerous,  in  i  row,  elliptical,  as  broad  as  the 
tracheid.  Pits  on  the  tangential  walls  of  the  summer  wood  chiefly 
confined  to  the  outermost  wall,  where  they  are  numerous,  apparently 
not  extending  beyond  the  second  wall,  small,  distinctly  lenticular. 
Resinous  tracheids  wanting.  ^ 

Tangential  Y^^Morm  rays  rather  few,  narrow,  the  cells  of  the  .short  termi- 
nals thick-walled,  tho.se  of  the  inflated  portion  very  thin-walled  and 
much  broken  down  or  wanting,  the  more  persistent  central  tract  with 
a  rather  small  resin  passage  with  delicate  epithelium.    Ordinary  rays 


|!'. 


310  ANATOMY  OF  THE  GYMNOSPERMS 

numerous,  nonrcsinous,  low  to  med'um,  slightly  contracted  by  the 
occasionally  interspersed  tracheids.  Parenchyma  ray  cells  not  very 
thick-walled,  equal,  rather  uniform  and  oval,  more  rarely  becoming 
either  round,  oval,  or  oblong;  sometimes  with  interspersed  thin-walled 
cells  of  similar  form  and  size. 

A  tree  15-30  m.  high,  with  a  trunk  upwards  of  2.40  m.  in  diameter. 
Wood  light,  soft,  not  strong,  very  close  grained,  and  compact. 

Specific  gravity 0557' 

Percentage  of  ash  residue 0.30 

Approximate  relative  fuel  value ',  ^^]^(, 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  yij. 

Ultimate  transverse  strength  in  kilograms 279! 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  5209! 

Resistance  to  indentation  to  1.27  mm.  in  kilograms       .     .  2140 
(Sargent) 

Dry,  gravelly  ridges  ;  mountains  of  southeastern  California,  Nevada,  north- 
ern Arizona,  and  southern  Utah  to  Colorado  above  7500  feet,  in  Colorado 
reaching  12,000  feet  (Sargent). 

6,  P.  edulis,  Engelm. 

PiitoH.     A'ut  Pine 

Transverse.  Growth  rings  narrow,  unequal.  Summer  wood  thin,  of  3-4 
tracheids,  and  not  prominent,  but  very  open  throughout ;  the  tracheids 
strongly  unequal  in  conspicuously  irregular  rows,  the  walls  thin,  the 
transition  to  the  spring  wood  gradual.  Spring  tracheids  open,  squarish, 
unequal,  and  in  more  or  less  irregular  rows,  the  walls  thin.  Medullary 
rays  not  very  prominent,  numerous,  rather  broad,  1  cell  wide,  dis- 
tant 2-7  rows  of  tracheids.  Resin  passages  numerous,  large,  the 
many-layered  epithelium  often  forming  extensive  tracts  composed 
of  large  and  very  variable,  often  thick  ailed,  somewhat  resinous 
cells. 

Radial.  Rays  very  sparingly  resinous ;  the  tracheids  marginal,  rarely  inter 
spersed.  Parenchyma  ray  cells  conspicuously  narrower  at  the  ends, 
short,  of  2  kinds:  (i)  the  upper  and  lower  walls  thick  and  entire  or 
distantly  pitted,  becoming  more  strongly  pitted  locally  or  in  the  sum- 
mer wood;  the  terminal  walls  generally  thick  and  coarsely  pitted  or 
rarely  thin  and  devoid  of  pits;  the  lateral  walls  with  small  and  round 
pits  with  a  variable,  often  obscure  border  and  a  lenticular  orifice,  1-4, 
more  rarely  5  or  6,  in  the  marginal  cells,  in  the  summer  wood  becomini; 
2,  per  tracheid ;  and  (2)  thin-walled  cells  sparingly  interspersed  and 
conterminous  with  those  of  the  first  kind  ;  the  terminal  walls  thin  and 
locally  thickened;  the  upper  and  lower  as  well  as  the  lateral  walls 
devro;d  of  pits.  Bordered  pits  numerous,  small,  elliptical,  in  1  row. 
Pits  on  the  tangential  walls  of  the  summer  tracheids  numerous  on  the 
outermost  wall,  becoming  fewer  in  the  older  tracheids,  rather  small 
and  broadly  lenticular.    Re.sinous  tracheids  wanting. 


PINUS 


3M 


7a//^.w///,,/.   Fusiform  rays  rather  nun,er,,us,  rhiefly  small  and  narrow  ■  tl.c 
inflated  portion  with  rather  large  and  very  thiii-wallcd  re  U   Vk^  '    • 

nTr^rici:!!  bv^he^^^-  T  'V  '"  ^^'^^^o^^^^, 
not  •■ei^tncted  by  the  equal  and  occasionally  interspersed  trachpi,k 

the  cells  ch.eriy  equal,  tather  uniform,  oval,  chiefly  narrow  -nd  thiJl' 

g7S;  Eght"''""" ""'  '"'^^^p^^'^^  ihin.waid"c:;s"oft:'„'^ii 

A  small  tree  6-9  m.  high,  with  a  trunk  upward,  of  .90  m.  in  diameter. 
Wood  hght,  soft  not  strong,  brittle,  close  grained,  compact,  and  durable  in 
contact  ..ith  the  soil.  uiauic  m 


Specific  gravity 

Percentage  of  ash  lesidue    . 

Approximate  relative  fuel  value 

Coefficient  of  elasticity  in  kilograms  on  millimeters  .'     ' 


0.6388 
0.62 

63.49 


iTi.:„    .     ,  ■'   -s,.-.iia  uii  iiiiiiiiiiciers  .     .     .        421 

Ultimate  .ran.sverse  strength  in  kilograms   .     .  7„ , 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  qc^S 

Res.st'.nce  to  indentation  to  1.27  mm.  in  kilograms  "^ 


(Sargent) 


9> 
78 
3388. 


Eastern  base  of  Pikes  Peak,  Colorado;  south  through  New  Mexico  to  the 
mountains  of  western  Texas.  Dry  mesas  and  slopes,  generally  on  lime  or 
sandstone,  reaching  elevati  mis  of  9000  feet  in  Colorado  (Sargent). 

7.  P.  Lambertiana,  Douglas 
Su^ar  Pine 

^'"'^  w7ht?'nn:'''.K"T.K'-'"'°^'  ""'^°™-     Summer  wood  about  one 
tSyJ^  ^^"^  ""^  •''P""«  ^°°d'   ^™'"   «hich   the  transition  is 
gradual,  the  structure  rather  open.    Spring  tracheids  large  squarish 
hexagonal,  in  regular  rows,  very  unifo'rm.ihe  walls  thir^^Xl  'ar- 
rays not  very'  prominent  or  numerous,  rather  broad,  i  cell  wide,  d"s  am 
th".  en  ,r'r°^  "■''''"^'-    ^"'=^  P^^^^'S^^  ^"y  '"f«e,  rather  numemus 
SreS'SlTvli^Tsir:"^  '''■'-'   '='>"^   ^-P-'^  °'  very  thD 
J^adial.  Rays  barely  if  at  all  resinous ;  the  tracheids  short,  rather  broad 
marginal  and  sparingly  interspersed  and  then  very  narrow    Parenchyma 
pitU    the  r  ^'  ''"^''^'  i.  "'t^PP^^  ^"d  '--  «-"«  .hin  and  oSe"y 

Se;ed     thTl"!      r'",,"^'".-:"''  ""'  P'"^^  »'"•  -sometimes  locally 
Uiickened  ;  the  lateral  walls  with  very  large,  oval  pits,  chiefly  ■>  oe. 
tracheid  throughout,  rarely  ,  or  3.    Bordered  pits  disti'^ic,  y  in  ,-2  mws 
numero  .;"h";"°»r-    '''V  '}'  *""«^"''="  -='"''  «f  ^^e  summer  wood 

orermost  Su'     «■■  ""'"  ^"'^  H^T^'^  '^"''"'"'  "«'  '^""Aned  to  the 
outermost  walls.    Resinous  tracheids  wanting 

Tangential.  Fusiforrn  rays  numerous,  large,  and  very  broad,  the  inflated 

portion  compo.sed  of  rather  thin-walled,  often  strongly  resinous  cells    he 

raZr  n^'  "■'""  P'"'«^  ""*•  "^'"-"^'"^d  epithefiu^m.    Ord  i^ar    riys 
rather  numerous,  nonresinous.  low  to  medium,  strongly  constricted  It 


312  ANATOMY  OF  THE  OYMNOSPERMS 

the  position  of  the  vei^-  narrow  and  small,  interspersed  tracheids  :  the 
l)arenchyma  cells  rather  equal  but  variable  from  broadly  to  nar- 
rowly oval,  the  thin  side  walls  sometimes  strongly  inflated,  rarely 
incurved. 

A  large  tree  46-92  m.  hifjh,  with  a  trunk  upwards  of  7  m.  in  diameter. 
Wood  very  light,  soft,    oarse,  but  straight  grained,  compact,  satiny,  and 
easily  worked. 

Specific  gravity 0.3684 

Percentage  of  a.sh  residue 0.22 

Approximate  relative  fuel  value 36.76 

Coefficient  of  elasticity  in  kilograms  on  millimeters  .     .     .  794. 

Ultimate  transverse  strength  in  kilograms  ....  255. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  5382. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  1244. 
(Sargent) 

Cascade  and  Coast  Ranges  of  Oregon,  where  it  descends  to  1000  feet  above 
.sea  level,  from  the  head  of  the  Mackenzie  River  and  the  valley  of  the 
Rogue,  southward  along  the  western  flanks  of  the  California  Sierra.s, 
where  it  reaches  an  elevation  of  4000-8000  feet ;  through  the  coa.st 
ranges  to  the  Santa  Lucia  Mountains,  and  in  the  San  Bernardino  and 
Cuyamaca  mountains  (Sargent). 


8.  P.  monticola,  D.  Don 

irAi/e  Pint 

Transverse.  Growth  rings  variable.  Summer  wood  open  and  very  thin  and 
imperceptibly  passing  into  the  spring  wood,  the  tracheids  in  regular 
rows,  variable,  squarish.  Spring  wood  very  open,  the  tracheids  large 
and  squarish,  rather  thin-walled.  Medullary  rays  prominent  and  resin- 
ous, not  numerous,  rather  broad,  i  cell  wide,  distant  2-17  rows  of  tra- 
cheids. Resin  passages  very  large,  rather  numerous,  the  epithelium 
rather  extensive  and  resinous. 

Radial.  Rays  conspicuously  resinous  throughout,  the  ray  tracheids  narrow, 
marginal,  often  interspersed.  Parenchyma  ray  cells  straight ;  the  upp«T 
and  loyver  walls  thin  and  entire  or  again  with  locally  numerous,  broad 
pits,  unequal ;  the  terminal  walls  thin  and  entire  or  again  locally  thick- 
ened ;  the  I  teral  walls  with  very  large,  oval  or  oblong  or  lenticular 
pits,  chiefly  1-2  per  tracheid  throughout,  in  the  summer  wood  reduced 
to  1  with  a  lenticular  orifice.  Bordered  pits  round  or  elliptical,  in  1  row 
or  sometimes  in  pairs.  Pits  on  the  tangential  walls  of  the  summer 
wood  small  and  narrowly  lenticular,  chiefly  on  the  outermost  wall. 
Resinous  tracheids  wanting. 

Tangential.  Fusiform  rays  not  numerous,  broad  and  high,  the  cells  of  the 
inflated  portion  large  and  thin-walled,  often  much  broken  down.  Ordi- 
nary rays  low  to  medium,  strongly  resinous,  when  of  a  few  elements 


PINUS  3,3 

Wood  very  light,  soft,  not  strong,  close  and  straight  grained,  and  con^pact. 
Specific  gravity 

Percentage  of  ash  resiuue     '. o-39o8 

Approximate  relative  fuel  value °  "3 

U     mate  transverse  strength  in  kilograms  .     .     .  "       Vol' 

ReZ^llT-''T  t«>"«i'"dinal  crushing  in  kilograms     c^ln' 

(Sargem)'     '"''"°"  '°  '''  """' '"  •''Wams^  l^l 

A  somewhat  uncommon  but  valuable  timber  tree,  usually  below  3000  feet 
elevation  in  British  Columbia,  but  rising  to  7ooo-.o'ooo  fie    in  cIl 

of  the  Fl^head  R.ver.  northern  Montana;  south  along  the  Cascade  Moun 
.a.ns  of  Wash.ng.on  and  Oregon,  and  the  California  Sierras  to  C  la  e  as 

B  S  C^ot\"'^l  '''"'''"'"  ''''*"'^'    ^"^^  ^«"^  -<»  Coast  rang 
Bnt..h  Columbm.  d.sappearing  at  an  elevation  of  2235  feet  (Macoun) 


m 


9.  p.  flexiUs,  James 

^yAite  Pine 

Tran^>erse.  Growth  rings  narrow,  rather  uniform.   Summerwood  very  thin 

>-2,  or  m  the  marginal  cells  more  rarely  3-4,  per  frachdd  in*^  ht' 
summer  wood  reduced  to  ,  and  lenticular.  ^  Bord^eJ  pits  el'limicar 
large,  in  i  row,  rather  numerous.  Pits  on  the  taneentiaV  wafls  oMhi' 
summer  wood  numerous  and  prominent,  broadl     uSiar   esLciallv 

ortrhydVw'Lrg^'"'^' -^"' ^--"^ ---^riirR^^^^ 

Ordinary  rays   numerous,   medium,  nonresinous,  not   conScuously 


I ''' 
If. 


3,4  ANATOMY  OK  THE  C.YMNOSPERMS 

contracted  l>y  the  sparioKly  intcrsijerscd  tracheidji ;  the  cells  ef|ual, 
oval,  and  uniform,  thin-walled ;  the  lateral  walls  not  concave  or 
convex. 

A  tree  15-18  m.  high,  with  a  trunk  upwards  of  1.20  m.  in  diameter. 
Wood  lijjht,  soft,  close  grained,  and  compact. 

Specific  gravity 0-435'* 

Percentage  of  ash  resid  ; 0.2S 

A|i|'ioximate  relative  fujl  value 43-42 

Coetficient  of  elasticity  in  kilograms  on  millimeters      .     .  676. 

Ultimate  tran.sverse  strength  in  kilograms       266. 

Ultimate  resistance  toll  n  itudinal  crushing  in  kilograms  5591. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  1727. 
(Sargent) 

Rocky  Mountains  of  British  Columbia  (Macoun) ;  southwai  1  through  the 
Rocky  Mountains  to  Utah,  Nevada,  New  Mexico,  and  Texas;  Inyo 
Mountains  and  Mount  Silliman,  California  (Sargent). 

10.  P.  refleza,  Engelm. 

irAtU  Pine 

Transiierse.  Growth  rinfs  variable,  often  double.  Summer  wood  conspic- 
uous but  thin  or  upwards  of  one  half  the  spring  wood,  from  which  the 
transition  is  gradual,  the  structure  open.  Spring  tracheids  large,  scjuar- 
ish-hexagonal,  the  walls  rather  thickish,  conspicuously  unequal,  and 
often  in  irregular  rows.  Medullary  rays  not  very  broad,  1  cell  wide, 
distant  2-10  rows  of  tracheid.s,  somewhat  prominent;  the  side  walls  dI 
the  cells  conspicuously  inflated  and  projecting  into  the  adjacent  tra- 
cheid  cavities.  Resin  pa.ssages  numerous  and  large,  chiefly  in  or  nc.ir 
the  summer  wood;  the  epithelium  composed  of  large  and  thin-walled, 
very  resinous  cells ;  when  in  the  summer  wood  the  resin  passage  is 
central  to  a  large  tract  of  thin-walled  tracheids. 

Radial.  Rays  nonresinous ;  the  tracheids  numerous,  low,  marginal,  and 
sparingly  interspersed.  Parenchyma  ray  cells  straight ;  the  upper  -nd 
lower  walls  rather  thick.sh  and  entire  or  again  somewhat  str  ..v'ly 
pitted,  especially  in  the  summer  wood ;  the  terminal  walls  thin  and 
entire  or  locally  thickened;  the  lateral  wall.s  with  large,  ovil,  or  s(iuar- 
ish  pits  which  finally  become  lenticular,  1-2,  chiefly  I,  pi  r  traclitid 
throughout.  Bordered  pits  numerous,  elliptical,  in  I  row,  distinctly 
smaller  and  round  toward  the  summer  wood  where  the  orifice  beconics 
a  more  or  less  extended  slit  merging  into  double  striations.  Pits  on  the 
tangential  walls  of  the  summer  wood  rather  small  and  flat,  narnnvly 
lenticular,  chiefly  confined  to  the  outermost  wall  where  they  are  ratlitr 
numerous.    Resinous  tracheids  wanting. 

Tangential.  Fu.siform  rays  broad,  rather  numerou.s,  the  cells  of  the  intlattd 
portion  very  large,  thin-walled.  Ordinary  rays  medium  to  low,  not  very 
numerous,  nonresinous,  rarely  contracted  by  smalle-,  interspersed  tra 
cheids  ;  the  parenchyma  cells  equal,  oval,  or  oblong,  the  thin  side  walls 
strongly  inflated,  more  rarely  incurved. 


FINUS  3,5 

Wood  I.Kht.  hard,  n,.t  strong,  dost-  Krainc.l.  .,n<l  c.mpact. 
Spicitic  Kraviiy  .... 

I'ercentaKf  <>f  a.sh  residue      . o-4«77 

(Sargent)  °-f' 

"*  r!^''''*T«  '"'';'"'''•■'  "'  """""  '"  '"^■-"''«=  -nons  at  eleva.ion.s  Letwcen 
6oa.a„d  8000  feet.    Hi,i.  .ountair,sof  southea.s.ern  New  Mexico.  .0 

11.  •  P.  strobus,  Linn. 
tf'hU  Pint.    Weymouth  Pine 

about  8  tracheids,  rather  con.spicuou.s.  variable  ind  rafh»r^L 
t  me.s  double;  the  tracheid.s  .squari.h/une  uaHn  retSJrows  ."h  T'"'' 
s...on  from  the  spring  wood  Udua'l.    Spri^  I'^^'oLr  he  r^^^^^^^^ 
large  but  very  unequal  tracheid.s  distinctlj  hexagonal  ^dthinVd led 
Medullary  rays  not  very  prominent  or  broad,  .  cell  wide    ew   distan; 
2-16.  or  more  rarely  30.  row.s  of  tracheid.s.    Resin  pa^s  nume'S', 
medium,  the  epithelium  .sparingly  resinous.  t'-'^-''=»>'CS  numerous. 

'f  :,  '^^^■■■*.  "°"'-«'*i"""«.  the  tracheids  long  and  low.  numerous  maririnal 
and  sparmgly  interspersed  when  they  are  verv  low     p!,^nM        ^ 
cells  straight,  equal  t';6-.s  spring  tra^-h^ids^L  upper  aTdirwaTl^ 
rather  th.ckish  and  entire  or  distantly  pitted;  the  t^mlnal  wills  thin 
and  ent.re  or  .somewhat  locally  thickened ;  the  latera   wafls  wt  h  ve  v 

IZ'^^clZ    Hord"'-''7'*:  '-'r  •"'^^^''^  throughout   n,ore  rare  • 
if^  •     ,  ■    "Offered  pits  rather  numerous  in  1  row   laru-e  sfrnn.rK- 

elliptical,  much  reduced,  and  finally  obscure  in  the  suni^erTo'cS  whe  L- 
the  orihce  becomes  a  prolonged,  diagonal  slit.  I'its  on  the  uTenti  ,1 
walls  o    the  -  ^^  „„^^^^„^  ,^^  ^^,^„_  chiefly  narrow  yLticu 

lar    Resinous  tracheids  wanting  '  'cmiLu 

^'"'Cnfl  fU''^'"''"  '-I''  ^""'  ""'  '•'^'y  '^'"^d,  nonresinous;  the  cells  of 
the   nflated  portion  large  and  thin-walled,  often  much  broken  out  or  fn 
small  branches  often  wholly  wanting.    Ordinary  rays  low  to  medTum  no^ 
ve  y  numerous,  narrow,  nonresinous;  the  celli  equal,  ra^h^r  unu'^rm 
oblong,  narrow,  the  side  walls  rarely  convex,  more'  general b  concave!' 

A  large  tree  of  the  greatest  economic  value.  24-52  m.  high,  with  a  trunk 
upwards  of  3.50  m.  in  diameter. 

Wood  light    .oft,  not  strong,  very  clo.se  and  straight  grained,  compact, 
easily  wor'    d.  and  susceptible  of  a  beautiful  polish. 

Specifi    gravity 

Percentage  of  ash  residue     .     .     . °-3«54 

Approximate  relative  fuel  value ,0"^ 

Coeflficient  of  elasticity  in  kilograms  on  millimeters '     '     '       gr ,  "^^ 
U  timate  transverse  strength  in  kilograms  .  '       ,67 

Ultimate  :  esistarice  to  longitudinal  crushing  i„  kilograms      6- lo 
Resistance  to  indentation  to  1.27  mm.  in  kilograms  ,  ,qI' 

(tiargent)  ■     .     ny^. 


s 


mi  I. 
PI 


'  \ 


3l6  ANAIOMY  OK  THE  GYMNOSPERMS 

The  following;  determinatinnH  are  after  Uovi-y  ; 
CfK;tTiticnl  of  <itri'ii);tli  in  jio  nuts    fur : 

Hiiiilii'U 4.800 

Torsioii 10,000 

Comprfssioii 3i5oo 

Shear 340 

VVci>{ht  JH-T  cutiic  fiioi .  26 

One  of  the  most  valuable  and  '..idely  spread  trees  of  Canada,  extending  frnin 
Newfoundland,  Anticnsti,  Nova  Scotia,  and  New  Brunswick  throuKhoui 
Quebec  and  Ontario,  and  westward  nearly  to  Lake  Winnipeg;  (Macoun) ; 
southward  through  the  northern  United  States  to  Pennsylvania,  the  south 
cm  shores  of  Lake  Michigan  ;  La  Salle,  Illinois  ;  Davenport,  Iowa  ;  alonj{ 
the  Allcjjhcny  Mountains  to  northern  Georgia  (Sargent). 

Pleistocene  deposits  of  the  Don  Period,  Toronto. 

Material  preserved  in  natural  state,  but  showing  the  effects  of  extended  decay. 


12.  P.  panriflora,  Sieb.  et  Zucc. 
/(;/.  =  llimtkomatsu 

Transverse.  Growth  rings  rather  broad,  the  usually  thin  summer  wood  up- 
wards of  one  half  the  spring  wckxI,  from  which  the  transition  is  gradual. 
Summer  wood  rather  n\i^\\,  often  double,  the  tracheids  conspicuously 
unequal,  rounded-he.xagonal.  Spring  tracheids  rather  large,  s<iuari.sli, 
uniform,  in  regular  rows,  rather  thin-walled,  radially  elongated.  Med- 
ullary rays  not  prominent  or  numerous,  very  narrow,  1  cell  wide,  dist.mt 
2-10  rows  of  tracheids.  Resin  pas.sages  large,  rather  numerous,  the 
epithelium  compo.sed  of  large  and  thin-walled  cells. 

Radial.  Rays  nonresinous  ;  the  tracheids  low,  marginal,  rarely  inierspersed. 
Parenchyma  ray  cells  straight,  eijual  to  about  5-7  .spring  tracheids  ;  the 
upper  and  lower  walls  very  variable,  chiei'y  rather  thin,  often  distanilv 
and  obscurely  pitted  ;  the  terminal  walls  thin  and  not  pitted  ;  the  lattra'l 
walls  with  large,  oval,  or  radially  elongated  simple  pits,  1,  or  in  the 
early  spring  wood  2,  per  tracheid,  in  the  summer  wood  liecoming  verti- 
cally lenticular.  Bordered  pits  very  large  and  narrowly  elliptical,  rather 
numerous,  in  1  row.  Pits  on  the  tangential  walls  of  the  summer  wood 
small,  rather  few  and  widely  scattering,  except  on  the  outermost  wall. 
Resinous  tracheids  apparently  wanting. 

Tani^ential.  Fusiform  rays  broad,  the  large  resin  canal  with  prominent 
thyloses  and  thin  epithelium  cells,  the  cells  of  the  inflated  portion  .dl 
thin-walled.  Ordinary  rays  narrow, conspicuou.sly  contracted  at  the  pusi- 
tion  of  the  much  narrower,  occasionally  interspersed  tracheids;  the 
parenchvma  cells  chiefly  equal,  rather  thin-walled,  somewhat  variable, 
chiefly  oblong  and  narrow  or  .sometimes  oval  and  much  broiHer,  but 
uniform  in  the  same  ray,  the  lateral  walls  concave,  more  rare  onvex. 
Re.sinous  tracheids  sparingly  present,  the  resin  in  plates  simulating 
Sanio's  bands. 


F.NUS  ^,y 

W.  P.  alblMulit,  Kiijjii, ,. 

H'llU  I'lHC 

'''''''^!^z::^^:::^^r-  ^t-— -.. ...nan,. 

HpriHK  wood  very  KraLsprr;.Xd!;i''  """  "'""'r'  '^"•"  ""= 
rather  uniform  in  reijular  rows  r.,h.  t  '^T,'  7l"'"-"''"Kxa«..n.,l. 
rather  l.road.  i  cc-l    tide    m  me'wh  •^.n-walled.     Mcluilary  ravs 

trachcids.  Resin  past  JesZl.un  r'uhl^r '""'•  •'"'"".  '"'  ^'"*''  "f 
and  .omewhat  resinous  epithrnunra,nui^",":'/''r''""''  "r"  .''^'""''"■"' 
cells.  Resinous  tracheids  ofV.  „  L'^r  ''"«'  '""'  "'i"-«->!^<l 
radial  series  contliuouft;  I'hl^LK';!.  'js  '""  ""  ••""^"•-  '-"'"•« 

medium,  variabr and  with  vihif""  '  .""  ""'•'^■^  ^""'  ''"v^'r^alfs 

pit.,  th^terminauithi^^nro  pi,;l'^^^r:'  '""  r."'^">-  ''^"•"' 
oval,  or  broadly  lenticular  nils  ■"  '  u  '  "^  '■'"'•''  "■'"^«'"'  l-'ricc 
Bordered  pits  nV^erou  C' r  ."un.l' in  ^'  ''  ''*'■ '''^'^'"•"l  <'-.u«hout. 
walls  of  the  summer  w^';„:,v^  V  •       '  '"^      '  "^  ""  ""■'  '^'"^-^n-i^'l 

chieflyontheoutc^nLt^nKeZ.  '?'■'■';"'•  .'"'•'^■^  "'"'"  "'"'  "■"• 
and  promine.-t    the  r  t  .Resinous  trada-Kls  somewhat  numerous 

and  sC"in«'sa:i:^.:',;;r"'«  '''•''-'  """"^'"--  •"•-•  -''""->•  r-ys 

U  ood  I.ght.  soft,  not  strong,  brittle,  close  grained,  and  compact. 

Specific  gravity 

Percentage  of  ash  residue 0.41  (-,5 

Approximace  relative  fuel  value °"^ 

CoefTicient  of  ela.sticity  in  kilograms ■on'millimc.trs'  '        ."f''^"* 

L  t.mate  transverse  strength  in  kilograms       .  '   "• 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms'  C-^Jl 
Re^.stance  to  indentation  to  ,  .27  n,m.  in  knograms^  :     ' 

(Sargent)  "  ■     .  i/io. 

Rocky  Mountains  of  Briti.sh  Columbia  between  6000  and  7000  feet  eleva- 
tion northward  to  latitude  53"  (Macoun)  ;  Cascade  and  Blue  mountains 
of  VVashington  and  Oregon  :  Scott's  Mountain.  M,,  Shasta,  and  the  high 
peak.s  of  the  Sierra  Nevadas  to  Mt.  San  Bernardino.  California.  Drv, 
gravelly  ndges  at  the  extreme  limit  of  growth,  in  the  San  Bernardino 
Mountains  attaining  an  elevation  of  ,0.500  feet,  and  at  the  highest  eleva- 
tions becoming  a  prostrate  shrub  (Sargent). 


3i8 


ANATOMY  OF   illK  OYMNOSPERMS 


Section  //.    Ht$rd  Pines 
14.  P.  clauM,  Sarg. 

.SiuHi/  /'/««•.    .Sfruh  I'lHt.    Sfruct  Vint 

Tranrftrst.  Growth  ritiK*  thick,  often  double.  Summer  wood  dense,  rarely 
Momewhat  open,  often  exceedinx  the  stprinu  wood,  from  which  the  tran- 
itition  is  usually  very  abrupt,  and  within  the  same  section  showinK  •x)th 
open  and  dense  structure  ;  the  tracheids  rounded,  unequal,  and  often  in 
irregular  rows.  Spring  tracheids  hexagonal,  not  very  uniform,  the  walK 
rather  thickish.  Kesin  pussaKes  larjje,  chieHy  in  the  summer  wood; 
the  epithelium  composed  of  lar^e,  round,  and  thin-walled  cells  chictly 
in  I  row,  occasionally  in  2  rows  and  forminn  more  or  less  eccentric 
tracts.  Medullary  rays  not  very  prominent  or  broad,  i  cell  wide,  distant 
2-8  rows  of  tracheids. 

Radial.  Rays  nonresinous  ;  the  tracheids  often  predominant  and  whin 
interspe  ted  often  l)ccomini{  very  low,  stronjjly  reticulated  throuKhoul. 
Ray  cells  cf  one  kind  only,  the  cells  rather  broad,  lonj?  fusiform  ;  the 
terminal  walls  thin  and  entire;  the  upper  and  lower  walls  very  thin; 
the  lateral  walls  with  very  variable,  lenticular,  or  oval  pits,  i-s,'chieHy 
2-3,  per  tracheid,  in  the  summer  woixl  reduced  to  i.  Hordered  pits 
conspicuously  i.i  1-2  rows,  elliptical,  in  the  summer  wood  abruptly 
reduced  to  14.4  /i,  and  finally  to  7.2  /i.  I'its  on  the  tangential  walls  of 
the  summer  wood  wholly  wanting. 

Tanj^cntinl.  Fusiform  rays  medium  to  hijjh,  rather  broad;  the  terminals 
acute,  somewhat  prolonged,  and  compo.sed  of  few  tracheids;  the 
inflated  portion  composed  of  very  large,  rounded,  and  usually  extrenv.  ly 
thin-walled  cells  among  which  there  may  l)c  an  occasional  traeheiii. 
Ordinary  rays  numerous  and  pre.senting  three  principal  ;is{}ects:  (1)  low 
rays  with  large  oval,  central  parenchyma  cells  and  small,  terminal  tr;i- 
cheids,  fusiform;  (2)  higher  rays  composed  of  large,  squarishcelleil 
and  thin-walled  parenchy  ma,  with  a  few  narrower,  termin.il  tracheids : 
and  (3)  the  highest  rays  compo.sed  of  large,  thin-walled,  oval,  and  broad 
parenchyma  cells  with  small  terminal  and  smaller  interspersed  tracheids 
causing  local  contractions. 

A  tree  21-24  m.  high,  wii'    a  trunk  upwards  of  .75  m.  in  diameter. 
Wood  light,  soft,  not  strong,  brittle. 

Specific  gravity ^ -^-f, 

Percentage  of  a.sh  residue 0.3 1 

Approximate  relative  fuel  value \     \  jj.oij 

Coefficient  of  ela.sticity  in  kilograms  on  millimeters      .     .  543. 

Ultimate  transverse  strength  in  kilograms 214. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  rx528. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms       .     .  2100. 
(Sargent) 

Barren,  .sandy  dunes  and  ridges  of  Florida;  shores  of  Pensacola  Bay  ami 
southward  within  30  miles  of  the  coast  to  Pea.se  Creek  ;  on  the  u.ist 
coast  occupying  a  narrow  ridge  south  of  St.  Augustine  (Sargent). 


i'lNLS  3,^ 

18.  P.  rigUc,  Mill. 
r,t,M  r,n, 

l)ei;<.inm),'  more  promineni  in  rhe  low  f  iv.  a'nri  i^.i.  "-■•u-'M) 

Of a-n  di.s,i„c,ly  bordered,  or  a«ai„  slm^le'^ndt^V  a  .blt^ Xn  ^ 
Hordcred  p„s  ,n  ,  r,,w  or  pairs,  dlip.ica).  Pits  on  the  tan«cn  i  "l  w^^^^^^ 
of  the  hummer  wood  wholly  wantiiiK  '-infctntial  walls 

/<7;/^r«/W   Fusiform  rays  not  very  nun.orojs,  rather  low  and  l.roul  •  .h,. 
em„nals  acute  and  compo.sed  c.f  a  lew  small  tracheidl ;  ,h  ■  celis  .V   t!. 

V  ru  nar>  ra)s  chiefl>  rather  low  and  presenting  two  principal  asix-tts- 
(0  low  rays  composed  of  thin-walled  parenchvma  much  roken  ou,' 
and  a  few  small,  terminal  tracheids  •  and  r-Thiirh-r  r  ..     *  i   ' 

parenchy„,a  cells  with  small,  terminal, '^nd  fji  '  l^^r  j  r^cLddT 
the  latter  causing  local  contractions.  iratncius, 

A  tree  .2-24  m.  high,  with  a  trunk  upwards  of  .90  m.  in  diameter 
W  ood  light,  .soft,  not  strong,  brittle,  coarse  grained,  and  con,pact.  ' 

Specific  gravity 

Percentage  of  ash  re.sidue °S'5' 

Approximate  relative  fuel  value °''^ 

Coefficient  of  elasticity  in  kilograms  on  millimeters   '     '     '       c8i' "'^ 
Ultimate  transverse  strength  in  kilograms  '     '     '       ,,/,' 

Ultimate  re.sistance  to  longitudinal  crushing  in  kilogranis  '     cf-Sy' 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  '     l,.\ 

(Sarj^eni)  *"  ■     •     •     -'-3- 

Valleyof  the  St.  John  River.  New  Brun.swick.  ,0  the  northern  shores  of 
Lake  Ontario  (Macoun);  south  through  the  Atlantic  states  to  Georijia  • 
westward  to  the  western  .slopes  of  the  Allegheny  Mountains  of  VvJst 
V  irginia  and  Kentucky  (Sargent). 


If     .! 


320 


ANATOMY  OF  THE  GYMNOSPERMS 


16.   P.  MTOtiiu,  Michx. 

Pond  Pine.     Afarsh  Pint 

Transverse.  Growth  rings  thick.    Summer  wood  dense  or  in  the  narrow 
rings  rather  open,  often  exceeding  the  spring  wood,  from  which  the 
transition  is  commonly  very  abrupt ;  the  tracheids  large  and  not  very 
uniform,   hexagonal,  in  very  regular  rows.    Spring  tracheids  large, 
squarish,  the  walls  thin.    Resin  passages  numerous  and  large,  chiefly 
in  the  summer  wood ;  the  epithelium  in  1 -several  rows  of  very  large, 
round,  and  dark  resinous  cells,  forming  an  extensive  tract  which  is 
often  strongly  eccentric  to  the  canal.   Medullary  rays  prominent,  broad 
I  cell  wide,  more  or  less  resinous,  distant  2-8  rows  of  tracheids. 
Radial.  Rays  more  or  less  resinous  throughout ;  the  tracheids  commonly 
predominant,  very  variable  in  height,  strongly  reticulated  throughout 
sparingly  interspersed.    Ray  cells  of  one  kind  only,  chiefly  rather  high 
more  or  less  fusiform,  equal  to  4-6  spring  tracheids,  resinous ;  the 
terminal,  upper,  and  lower  walls  thin  and  usually  much  broken  out  • 
the  lateral  walls  with  very  variable,  lenticular  pits,  1-4,  rarely  5,  per 
tracheid,  becoming  very  narrow  and  much  prolonged  slits  in  the  sum- 
mer wood.    Bordered  pits  in  I  row  or  somewhat  frequently  in  pairs, 
and  thus  more  or  less  2-rowed,  round,  or  elliptical.    Pits  on  the  tan- 
gential walls  of  the  summer  wood  wholly  wanting. 
Tangential.  Fusiform  rays  rather  numerous,  resinous,  narrow,  medium  to 
high,  the  terminals  acute,  more  rarely  prolonged,  and  composed  of 
small  tracheids ;  the  inflated  portion  composed  of  large,  thin-walled 
cells  usually  much   broken   out.    Ordinary  rays  medium,  numerous, 
broad,  resinous,  and  presenting  three  principal  aspects  :  ( 1 )  low  rays  of 
i-several  thin-walled,  resinous  parenchyma  cells  with  small,  termi- 
nal tracheids  ;  (2)  higher  rays  chiefly  composed  of  very  large,  oblong, 
and  often  strongly  reticulated  tracheids  with   i   or  2  large,  resinous 
parenchyma  cells  much  broken  out ;  and  (3)  the  highest  rays  of  several 
oblong,  resinous  parenchyma  cells   with  few  terminal    tracheids,  or 
again  variously  contracted  through  the  presence  of  small,  interspersed 
tracheids. 

A  tree  12-24  m.  high,  with  a  trunk  upwards  of  .90  m.  in  diameter. 
Wood  heavy,  soft,  not  strong,  brittle,  coarse  grained,  and  compact. 

Specific  gravity ^  ^g ,3 

Percentage  of  ash  residue 0,7 

Approximate  relative  fuel  value    .........  79.29 

Coefficient  of  elasticity  in  kilograms  on  millimeters  .11 70." 

Ultimate  transverse  strength  in  kilograms       497. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  8079! 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .  4740 
(Sargent) 

An  uncommon  species  in  low,  peaty  soil,  ponds,  and  along  the  borders  nf 
streams.  North  Carolina  and  south  near  the  coast  to  tli.-  head  of  the 
St.  John's  River,  Florida  (Sargent). 


PINUS  ,^, 

17.   P.  Banksiuu,  Lamb. 
Scrub  Pint.     Gray  Pine.    Jack  Pme 

^''""oTe  h^f?h?r"''-  ""^'  rr°^'  ""'^°™-    S"'"'""  *ood  dense,  about 

tra,-f     M^j  II  "iii-ii  waiiea  ceil,  the  whole  formine  an  eccentrir 

r^ororof'Shei^s;^^  ^"^  '^™=^'''  ^°--''-  PromLnt!"St 

'^'^'I'dl^^'.-f''"'"^'^''^"'"''""'  *^  ray  tracheids  strongly  predominant 
R.V  n/.I     \  T'  r ^  '''°"S'>'  ^'^''^"lated  throughout!  fntersZ^j 

7««<r^«/W.  Fus,form rays  rather  low  and  rarrow,  raSlw  th^e  terminals 
acute  or  somewhat  prolonged  and  chiefly  composed  o^rfchS  the 
Dretn  O  'f^'"^  ^°''r  ^"^'  ^"^^  '^'l'"  thin-walied  generally  a" 
S  ipecL  n^  T  '""  '"''  '''^''>;  "='"°^'  P--"tin|three  p^rin 
;h?n,„t^f!i  (I)  low  rays  composed  of  oblong  or  narrowly  oval 
th,n-walled  parenchyma  cells  with  narrowly  oblong  terminal  ra- 
cheids  ;  (2)  low  rays  of  similar  composition,  but  the  parenchTm^  cllU 

U-ood"l''.'f  ^7  "■  "'"•  "'"  '  ''""'  ■■-«')• -"-ding  .75  m.  in  diameter. 
W  ood  light,  soft,  not  strong,  rather  close  grained,  and  compact. 

Specific  gravity      ... 

Percentage  of  a.sh  residue °"}^ 

Approximate  relative  fuel  value  °'^^ 

Coefficient  of  elasticity  in  kilograms  on  millimeters'     '     *       042"^° 
U  timate  tran.sverse  strength  in  kilograms  ,,« 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms'     6320 

(S^riLn  ''°"*°''^  'S 

Halifax  Nova  Scotia,  northwesterly  to  the  Athabasca  River  and  down  the 

,    Mackenzie  River  to  the  Arctic  Circle  ;  eastward  it  hardly  becomes  a  tree. 

but  westward  it  increases  in  size,  and  westward  of  Lake  Winnipeg  i 


i 


322 


ANATOMY  OF  THE  GYMNOSPERMS 


equals  the  red  pine  of  the  east  in  height  and  diameter  (Macoun) ;  south- 
ward through  northern  Maine ;  at  Ferrisburg,  Vermont  j  thence  westward 
along  the  southern  shores  of  Lake  Michigan  to  central  Minnesota. 
Barren,  sandy  soil,  more  rarely  in  rich  loam  (Sargent). 


¥' 


w 


18.   P.  contorta,  Loud. 

Strut  Pine 

Tranmerse.  Growth  rings  thick.  Summer  wood  dense,  conspicuous,  often 
exceeding  (he  spring  wood  ;  the  tracheids  in  regular  rows,  those  in  the 
outer  portion  generally  much  compressed,  variable,  those  of  the  central 
portion  more  uniform  and  with  rounded  lumens;  transition  from  the 
spring  wood  gradual.  Spring  tracheids  hexagonal,  unequal,  in  regular 
rows,  the  walls  rather  thin.  Resin  passages  scattering,  numerous, 
small ;  the  epithelium  in  1-3  rows  of  angular,  thin-walled  cells  which 
merge  outwardly  into  thicker-walled  elements,  the  whole  forming  an 
irregular  and  somewhat  extended  tract.  Medullary  rays  rather  narrow, 
I  cell  wide,  not  prominent,  rather  numerous,  distant  2-12  rows  of 
tracheids. 

Radial.  Rays  nonresinous ;  the  tracheids  numerous,  low,  sparingly  inter- 
spersed and  sometimes  predominant,  distinctly  reticulated  throughout. 
Ray  cells  of  one  kind  only  and  variously  fusiform;  the  terminal, 
upper,  and  lower  walls  very  thin  and  often  much  broken  out  or  wholly 
wanting ;  the  lateral  walls  with  large,  oblong,  or  lenticular  pits  which 
often  become  round  or  oval  when  the  ray  is  only  i  cell  high,  and  on 
the  inner  face  of  the  spring  wood  in  all  rays,  1-4,  chiefly  2-3,  per 
tracheid,  in  the  summer  wood  greatly  reduced  in  size,  shape,  and 
number.  Bordered  pits  in  i  row,  sometimes  in  pairs,  elliptical, 
becoming  much  reduced  and  remote  in  the  summer  wood.  Pits  on 
the  tangential  walls  of  the  summer  wood  wholly  wanting. 

Tangential.  Fusiform  rays  not  numerous,  medium  ;  the  terminals  acute, 
rarely  somewhat  prolonged,  and  composed  of  small  tracheids  ;  the  cells 
of  the  inflated  portion  all  very  thin-walled  and  generally  broken  out. 
Ordinary  rays  medium,  rather  numerous,  the  thin-walled  parenchyma 
cells  predominant,  commonly  broken  out  so  as  to  leave  the  ray  vacant 
for  nearly  the  whole  height,  the  tracheids  ch:..'iy  terminal  but  occa- 
sionally interspersed  as  somewhat  narrower  and  rounded  elements, 
causing  local  but  slight  contraction. 

A  small,  stunted  tree  6-9  m.  high,  with  a  trunk  upwards  of  .50  m.  in  diameter. 
Wood  light,  hard,  strong,  brittle,  and  coarse  grained. 

Specific  gravity 0.5815 

Percentage  of  ash  residue o.ig 

Approximate  relative  fuel  value 58.04 

Coefficient  of  elasticity  in  kilograms  on  millimeters       .     .  1585. 

Ultimate  tran.sverse  strength  in  kilograms        423. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  8868. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms       .     .  2382. 
(Sargent) 


Columbia  along  the  coast  to  m!!V  ^  southward  from  British 

19.   P.  glabra,  Walt. 
CtJar  Pine,     spruce  Pine.     Whitt  Pine 

""TriSw^o^lmThiJfthe  t'""^"  ^^  ''  ^^"»  o-  l-alf  the 

doubfe  or  treb!nhe"Srl?;orr„''de"n;:  "1?'?.^°"'^*'^^*  ='''^"P'' 
especially  when  double  or  trehll  tKl  ?  'u  •!■  °"'^''  Po^'ons  open, 
regular  rows.  Spring  tracheidshiv,  t'^''^ -I"  ""^"  ^^"^^le,  in 
the  walls  thin.  K  ptos  "^hT"!'  "i?'^"""  '"  ^^S'"^'"  ^«>w«. 
thelium  in  1-2  rows  of  C^r^  J  !'  abundant,  medium;  the  epi- 
irregular  cells  usurnymuc7b;oK^    Tf  ";'"-^."ed.  resinous  and 

tracts.  Medullary  rays  no'ver?  broad  nromi?.  °'''^'"«  ^^""^  "'^"'^^'^ 
2-12  rows  of  tracheids  ^  '  P'^"'""'^'".  ^^  numerous,  distant 

and  becoming  rshmsm^'^*^:^^^^  finally  reduced  to 

summerwood%oonrSuce^itOQ6  'S/n   fi"  '  J?^^' ^"iP'ical,  in  the 

aspects:  0)  r"-.  S^  T,        '  '1"^  ^•••"linS  l»o  principa] 

c«po.rt  „,  |„g;,  toSeTpLSZl  SL  S  7^  ■'=*,  ">3 
interspersed,  chiefly  DrpHomino„»      J    ^  *"*"  termmal  and 

contraction  ^  P«dom.nant  and  narrower,  tracheids  causing  local 

wi'cJiltf  w;  "^^  ""''  '  '™"'  "P^^^*^-^  ''^  '-^^  >"•  '■"  diameter. 
Wood  hght,  soft,  not  strong,  brittle,  very  coarse  grained,  not  durable. 

Specific  gravity 

Percentage  of  ash  residue °-393i 

Approximate  relative  fuel  value °''5 


1^1^     Jr     i 


:11 


mm 


324 


ANATOMY  OF  THE  GYMNOSPERMS 


South  Carolina  to  the  Chattahoochee  region  of  Florida,  chiefly  near  the 
coast,  thence  through  the  Gulf  States  south  to  latitude  32°  30'  to  the 
valley  of  the  Pearl  River,  Louisiana,  iu  greatest  development  being  ii. 
Alabama  and  Mississippi  (Sargent). 


ii« 


•  I'* 


20.  P.  echinaU,  Mill. 
Ytllow  Pine.    Short-Leaved  Pine 

Transtitrse.  Growth  rings  thick.  Summer  wood  thick,  very  prominent, 
dense,  and  often  exceeding  the  spring  wood  from  which  the  transi- 
tion is  generally  very  abrupt ;  the  tracheids  unequal  in  regular  rows, 
but  varying  greatly  in  different  growth  rings  so  that  the  structure 
pres-nts  a  very  variable  density.  Spring  tracheids  large,  squarish- 
hexagonal,  the  walls  thin.  Resin  passages  numerous  but  large  and 
scattering;  the  epithelium  composed  of  i  row  of  thin-walled  cells,  less 
frequently  becoming  2-rowed  in  part,  the  cells  often  resinous.  Medul- 
lary rays  prominent,  rather  broad,  numerous,  distant  2-8  rows  of 
tracheids. 

Radial.  Rays  somewhat  resinous  throughout;  the  ray  tracheids  rather 
high,  conspicuously  predominant  and  very  strongly  reticulated  through- 
out, often  composing  the  entire  ray.  Ray  cells  of  one  kind,  rarely  of 
two  kinds,  few,  interspersed,  fusiform ;  ti..'  terminal,  upper,  and  lower 
walls  very  thin  and  much  broken  out ;  the  lateral  walls  with  very 
variable,  lenticular  pits,  1-4  per  tracheid,  becoming  more  or  less  obso- 
lete in  the  summer  wood.  Bordered  pits  in  i  row  or  pairs,  rarely 
2-rowed,  elliptisal,  in  the  summer  wooid  reduced  to  7.2  /i,  when  the 
orifice  often  becomes  obscure  or  eccentric.  Pits  on  the  tangential 
walls  of  the  summer  wood  wholly  wanting. 

Tangential.  Fusiform  rays  rather  numerous,  high,  the  terminals  prolonged, 
linear,  and  composed  of  broad  parenchyma  cells  with  terminal  tra- 
cheids ;  the  cells  of  the  inflated  portion  very  thin-walled  and  usually 
all  broken  out.  Ordinary  rays  rather  numerous,  high,  presenting  two 
principal  aspects:  (i)  low  rays  composed  of  thin-walled  parenchyma 
much  broken  out,  and  small,  terminal  tracheids  ;  and  (2)  higher  rays 
composed  of  oblong  tracheids  with  few,  interspersed,  broader  cells  of 
thin-walled  parenchyma,  thus  causing  local  expansions. 

A  tree  24-30  m.  in  height,  with  a  trunk  upwards  of  1.35  m.  in  diameter. 
Wood  varying  greatly,  heavy,  hard,  strong,  generally  coarse  grained,  and 
compact. 

Specific  gravity 0.6104 

Percentage  of  ash  residue 0-29 

Approximate  relative  fuel  value 60.86 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  I37S- 

Ultimate  transverse  strength  in  kilograms 443- 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  7628. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  2064. 
(Sargent) 


PINUS 


325 


Staten  Island,  New  York,  thence  southward  to  western  Florida  and 
throujjh  the  Gulf  States  to  Tennessee  and  eastern  Texas;  thrru^h 
Arkansas  to  Oklahoma;  southeastern  Kansas,  southern  Missouri,  and 
in  Union  County,  Illinois  (Sargent). 


21.  P.  reainou,  Ait. 

Red  Pine.     Norway  Pint 

7><7««/<rrw  Growth  rings  very  thick,  often  double.  Summer  wood  about 
one  fifth  the  spring  wood,  from  which  the  transition  is  very  gradual  • 
not  very  dense,  but  when  double  the  outer  band  is  generally  mor'"  open 
with  the  tracheids  less  compressed,  the  inner  band  is  more  dense  with  the 
tracheids  usually  thick-walled  and  more  conspicuously  compressed  • 
the  tracheids  round-hexagonal,  conspicuously  unequal  in  regular  rows 
the  walls  rather  thick.  Spring  tracheids  hexagonal,  uniform  in  regular 
rows,  the  walls  thickish.  Resin  passages  very  scattering,  not  numer- 
ous, large  ;  the  epithelium  not  extensive,  about  2  layers  thick,  the  cells 
of  the  layer  next  the  canal  radially  flattened,  those  of  the  other  layers 
oval,  often  resinous.  Medullary  rays  rather  prominent  and  broad, 
numerous,  distant  2-9  rows  of  tracheids. 

Radial.  Rays  nonresinous,  the  ray  tracheids  low,  marginal,  rarely  inter- 
spersed, conspicuously  dentate.  Ray  cells  long  and  low,  straight,  or 
m  the  summer  wood  often  conspicuou-sly  contracted  at  the  ends  •  the 
terminal  walls  thin  and  entire ;  the  upper  and  lower  walls  rather  thin, 
remotely  and  miperfectly  pitted ;  the  lateral  walls  with  very  large, 
oval  or  oblong,  very  variable  pits,  which  become  lenticular  toward  the 
summer  wood,  1-2,  chiefly  i,  per  tracheid  throughout.  Bordered  pits 
in  I  row,  sometimes  in  pairs,  elliptical.  Pits  on  the  tangential  Walls  of 
the  summer  wood  wholly  wanting. 

Tangential.  Fusiform  rays  not  numerous,  chiefly  rather  low  and  broad,  the 
cells  rather  large  and  thin-walled  throughout.  Ordinary  rays  medium, 
nonresinous,  numerous,  rarely  contracted  by  much  smaller  and  nar- 
rower, interspersed  tracheids;  the  cells  chiefly  equal  but  not  very 
uniform,  oval  or  squarish,  rather  large,  and  thin-walled,  the  lateral 
walls  very  thin  and  chiefly  concave. 

A  tree  24-46  m.  high,  with  a  trunk  upwards  of  1.37  m.  in  diameter. 
Wood  light,  not  strong,  hard,  rather  coarse  grained,  and  compact. 

Specific  gravity 0.4854 

Percentage  of  ash  residue 0.27 

Approximate  relative  fuel  value 48.41 

CoeflScient  of  elasticity  in  kilograms  on  millimeters  .     .     .  1132. 

Ultimate  transverse  strength  in  kilograms 341. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  .  7274. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  .     .     .  1353. 
(Sargent) 


.5| 

Ms 


M 


326  ANATOMY  OF  THE  GYMNOSFICRMS 

The  following  determinations  are  after  Bovey  ; 

Coefficien   il  strength  in  pounds  for: 

Bending SA^o 

Elasticity 1,430,000 

Torsion 11,500 

Compression 3<9°° 

Shear 380 

Weight  per  cubic  foot 33 

Rather  a  widely  distributed  but  somewhat  localized  tree  flourishing  partic- 
ularly in  the  poorest  soils :  Nova  Scotia,  New  Brunswick,  Quebec,  and 
w;;stward  to  Lake  of  the  Woods  (Macoun) ;  through  the  New  England 
States  to  northern  Pennsylvania  and  westward  to  Michigan  and  central 
Minnesota  (Sargent). 

22.  P.  tropicalis,  Morelet 

Trami'trse.  Growth  rings  narrow,  unequal.  Summer  wood  chiefly  rather 
dense  but  somewhat  variable,  usually  exceeding  the  spring ;  the  tra- 
cheids  hexagonal-oblong,  uniform,  and  in  regular  rows  ;  transition  from 
the  spring  wood  abrupt  or  more  rarely  gradual.  Spring  tracheids 
large,  conspicuously  squarish  or  hexagonal,  the  walls  rather  thin. 
Medullary  rays  prominent,  resinous,  1  cell  wide,  broad,  distant  2-8,  or 
more  rarely  12,  rows  of  tracheids.  Resin  passages  num»»-ous,  large, 
resinous,  and  chiefly  confined  to  the  summer  wood ;  the  epithelium  of 
1-2  rows  of  thin-walled  cells  which  often  form  tangentially  extended 
tracts. 

Radial.  Ray  tracheids  rather  low  and  rather  sparingly  dentate,  never  reticu- 
late ;  numerous  and  interspersed,  often  predominant.  Medul'.i  y  ray.s 
rer.inou.s,  the  cells  all  of  one  kind ;  the  upper,  lower,  and  term.  x\  walls 
thin  and  commonly  much  broken  down ;  the  side  walls  with  larxe, 
oval,  oblong,  or  lenticular  pits,  1-2,  chiefly  1,  per  tracheid,  in  tht- 
summer  wood  often  reduced  and  vertically  lenticular.  Tits  on  the 
tangential  walls  of  the  summer  tracheids  wholly  wanting,  but  often 
appearing  on  the  tangential  walls  of  the  first  spring  tracheid.  Bor- 
dered pits  large,  in  I  row  or  in  pairs,  the  latter  often  approximating  so 
as  to  form  2  rows ;  in  the  summer  wood  becoming  much  reduced  and 
rather  di.stant  in  1  row. 

Tangential.  Fusiform  rays  somewhat  numerous,  medium  ;  the  terminals 
somewhat  prolonged  but  usually  acute  and  composed  of  few,  thick 
walled  tracheids  ;  the  cells  of  the  central  tract  all  thin-walled  and  much 
broken  out.  Ordinary  rays  numerous,  very  resinous,  medium  ;  the  cells 
oval,  uniform,  and  equal  but  much  broken  out ;  the  higher  rays  some- 
what contracted  by  the  interspersed,  rather  smaller,  and  thick-walled 
tracheids. 

Cuba  and  Isle  of  Pines,  West  Indies. 

A  careful  comparison  of  this  wood  with  that  of  P.  resinosa  will  show  th.it 
while  they  are  very  closely  related,  there  are,  nevertheless,  essential  struc- 
tural differences  which  compel  us  to  recognize  them  as  distinct  spet  its. 


PINUS 


327 


M.  P.  ThunbergU,  Pari. 

Jap.  =  A'uromn/sH 

Transr-erse.  Growth  rings  rather  broad,  variable.    Summer  wood  dense 
sometimes  equal  to  the  spring  wood  from  which  the  transitionTs 
abrupt,  rarely  gradual,  often  double;  the  rounded  tracheids  ra"her 
equal  in  regular  rows.    Spring  tracheids  large,  hexagonal,  unequal 
m  regular  rows,  the  walls  rather  thin.    Resin  passages  ,;thernu 
merous,  rather  large  and  scattering;  the  epithelium  in  .-^ rows  of 
very  large  and  very  thin-walled  cells  not  extending  much  beyond  the 
central  canal;  nonresinous;  in  the  summer  wood  the  layer  next  the 
canal  is  much  compre.ssed  and  the  cells  are  barely  recognizable    Med- 
Sldr       '■  "°'  ^"^  ''™'"*  °'  prominent,  distant  2-8  rows  of 
Radial   Rays  nonresinous ;  the  ray  tracheids  more  or  less  dentate  but  not 
re  iculate,  generally  predominant  and  marginal,  not  interspersed.    Rav 
cells  of  one  kind  only,  straight ;  the  terminal  walls  thin  and  entire  •  the 
upper  and  lower  walls  thickish  and  entire  or  distantly  and  obscurely 
pitted;  the    ateral  walls  with  very  large,  oblong,  or  lenticular  pits 
almost  strictly  .,  rarely  2,  per  tracheid.  in  the  summer  wood  KomTg 
distinctly  bordered,  when  they  are  broadly  oval  with  a  long,  slitlike 
orifice.    Bordered  pits  large,  elliptical,  not  very  numerous,  in  1  row 
Pits  on  the  tangential  walls  wholly  wanting. 
Ta,tf:entiai.  Fusiform  rays  rather  numerous  but  low  and  broad,  the  chiefly 
rather  short  terminals  wholly  composed  of  small,  oval  tracheids.  and 
a  few  parenchynria  cells,  the  inflated  portion  composed  of  very  thir- 
walled  cells  much  broken  out.    Ordinary  rays  rather  numerous,  low  to 
medium,  nonresinous,  not  very  broad  but  presenting  two  principal 
aspects:  (I)  narrow  rays  composed  of  a  few  central,  oval  parenchyli-a 
cells  and  several  variable,  terminal  tracheids;  and  (2)  broader  rays 
composed  of  oval  parenchyma  cells  and  a  few  terminal  and  small 
tractieios. 


t 

•'i 


'     1     t 


24.  P.  densiflora,  Sieb.  et  Zucc. 

yap.  =  Akamatsu 

Tranmerse  Growth  rings  very  uniform.  Summer  wood  one  half  the  spring 
wood,  froin  which  the  transition  is  abrupt,  chiefly  dense  but  somewhat 
variable,  the  tracheids  rounded,  unequal  in  regular  rows.  Spring  tra- 
cheids hexagonal,  rather  uniform,  in  regular  rows,  the  walls  thicki.sh 
Kesm  passages  numerous,  large,  scattering;  the  epithelium  in  1-2 
rows  of  thin-  and  thick-walled  cells,  easily  broken  out  and  generally 
wanting,  nonresinous.  Medullary  rays  few,  not  very  prominent,  very 
narrow,  rather  obscure,  distant  2-20  rows  of  tracheids. 

Kadial.  Rays  nonresinous ;  the  ray  tracheids  dentate,  sparingly  reticulate 
in  the  summer  wood,  usually  predominant  and  marginal,  sparingly 
interspersed.  Ray  cells  of  one  kind  only  and  straight :  the  terminal 
walls  thin  and  entire ;  the  upper  and  lower  walls  thin,  somewhat  uni- 
form, not  obviously  pitted;    the  lateral  walls  with   very  large  and 


328  ANATOMY  OK  THE  (iVMNOSPERMS 

simple,  oblonR,  or  oval  pits,  almost  strictly  i  per  tracheid,  in  the 
summer  wood  distinctly  bordered  and  then  larj^,  oval,  with  a  broad, 
oblonK  orif  e.  Bordered  pits  large,  elliptical,  rather  numerous,  in 
I  row.  I'lt:;  on  the  i.inKentiai  walls  of  the  summer  wood  wholly 
wanting. 
Tangential.  Fusiform  ra)s  r.ilher  numerous,  medium,  narrow,  the  slightly 
prolonged  terminals  com|i<)sed  of  a  few  small  tracheids  ;  the  gradually 
inflated  portion  composed  of  very  thin-walled  cells  all  broken  out. 
Ordinary  rays  medium,  rather  numerous,  not  very  broad  and  present- 
ing two  principal  aspects:  (i)  low  to  medium  rays  composed  of 
i-several  oval  parenchyma  cells  with  small,  terminal  tracheids  which 
often  become  predominant ;  and  (2)  the  highest  rays  with  numerous 
tracheids  and  few,  interspersed  parenchyma  cells. 


25.  P.  Mumyana,  A.  Murr. 
Black  rint.    Lodgt  Poll  Pine.     Spruce  Pint 

Trann'trse.  Growth  rings  usually  broad.  Summer  wood  very  thin,  the 
structure  very  open  throughout,  the  transition  from  the  spring  wood 
very  gradual ;  the  tracheids  compressed,  unequrl,  rather  squarish,  in 
.somewhat  irregular  rows.  Spring  tracheids  somewhat  squarish-hex- 
agonal, often  in  very  irregular  rows,  unequal,  the  walls  thin.  Resin 
passages  rather  small  and  scattering;  the  epithe.ium  in  1  row  of  very 
large  and  thin-walled,  somewhat  radially  flattened,  nonresinous  cells, 
immediately  inclosed  by  a  layer  of  large,  thin-walled  tracheids.  Med 
ullary  rays  prominent,  broad,  i  cell  wide,  numerous,  distant  2-9,  more 
rarely  1 1  rows,  of  tracheids. 

Radial.  Rays  uniformly  somewhat  resinous  throughout ;  the  ray  tracheids 
sparingly  dentate,  more  or  less  reticulate  in  the  summer  wood,  mar- 
ginal and  interspersed,  often  predominant.  Ray  cells  apparently  of 
two  kinds,  but  merging  so  as  to  be  more  or  less  indistinguishable, 
strongly  but  variously  fusiform  ;  the  terminal  walls  thin  and  entire  or 
locally  thickened ;  the  upper  and  lower  walls  either  entire  or  locally 
and  irregularly  thickened,  thin ;  the  lateral  walls  with  rather  small, 
round,  oval,  or  lenticular  pits,  at  first  simple,  but  toward  and  in  the 
summer  wood  with  a  more  or  less  obvious  border  and  oblong  orifice, 
1-4,  rarely  5,  per  tracheid,  in  the  summer  wood  reduced  to  1-2.  Bor- 
dered pits  in  I  row,  sometimes  in  pairs,  not  much  crowded  but  strongly 
elliptical.  Pits  on  the  tangential  walls  of  the  summer  wood  wholly 
wanting. 

Tangential.  Fusiform  rays  low,  few  and  small,  rather  broad,  more  or  les.s 
unequal,  acute  or  somewhat  prolonged,  the  cells  rather  small  ami 
thick-walled  throughout,  the  central  tract  usually  much  broken  out. 
Ordinary  rays  numerous,  broad,  when  a  few  cells  high  conspicuously 
fusiform  ;  the  high  rays  commonly  contracted  at  the  position  of  small 
and  frequently  interspersed  tracheids;  the  parenchyma  cells  rather 
thin-walled,  round,  or  transversely  oval,  very  unequal  and  variable,  the 
higher  rays  commonly  showing  smaller  and  thicker-walled  cells  either 
singly  or  in  pairs. 


PINUS  3,^ 

A  tree  18-24  m.  hlRh,  with  .1  trunk  upward,  of  1.20  m.  in  diameter. 
Wood  I.Kht.  soft,  not  stronK.  close  and  st.aiKht  grained,  ea.ily  worked, 
compact,  not  durable.  '  * 

Specific  gravity 

Percentage  of  a.sh  resiidue    .     .     . 0.4096 

Approximate  relative  fuel  value °'l^ 

Coefficient  of  elasticity  in  kilogram.,  on  miilimeters*     '.     ."       77,    ^ 

Ultimate  transverse  strength  in  kilogram.,  i..' 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms'  ci's' 

ResLstance  to  indentation  to  1.27  mm.  in  kilograms     .  ^lla' 

(Sargent)  ^'^• 

An  Alpine  tree  somewhat  localized  in  the  Rocky  Mountains  of  British 
Columbia  at  elevations  of  3500-4000  feet,  and  northward  to  latitude 
62  (Macoun)  ;  mountain  ranges  of  Washington,  Oregon,  and  the  Sierra 
Nevadas  of  California  to  San  Jacinto;  southward  through  the  moun- 
tains of  Idaho,  Montana,  Wyoming,  Colorado,  and  Utah  to  New  Mexico 
and  northern  Arizona.  The  tree  attains  it  greatest  development  in  the 
California  Sierra.s,  in  the  interior  occurring  on  dry,  gravelly  soil  cover- 
ing immense  areas.  In  the  Rocky  Mountain  region  it  or  upies  the 
borders  of  moist  Alpine  meadows  between  6000  and  9000  feet  elevation 
(Sargent). 

26.  P.  urlzonica,  Engelm. 

ytllmi  Pint 

^''"TIh ';i,^"'^*'*  r""^  *^'''*''>'  *''''=''  •'"'  variable,  often  double.   Summer 
wood     hu.    of  about  4-«o  tracheids  but  very  variaL'e,  usually  v^ry 
open ;  the  tracheids  very  unequal,  now  small  and  round  or  again  large 
and  much  compressed,  often  in  very  irregular  rows  ;  transition  from 
the  spring  wood  somewhat  gradual.    Spring  tracheids  arge,  hexagonal 
uniform,  m  regular  rows,  the  walls  thin.    Re.sin  passages  verXge 
rather  abundant;  the  epithelium  in  2  rows,  that  next  The  canil  con^! 
posed  of  large  and  rather   thin-walled  cells  which  are   immediately 
bounded  by  a  layer  of  rather  thick-walled,  large,  rounded,  and  often 
resinous  cells.     Medullary  rays  broad,  .  cell  wide,  rather  prominent" 
sparingly  and  ocally  resinous,  distant  2-.0  rows  of  tracheids.  ' 

kadial   Rays  locally  resinous;  the  ray    tracheids  strongly  predominant, 
strongly  dentate,  and  somewhat  reticulated  in  the  summer  wood.    Ray 

w^in?r"fM^-"^°T  ^"'^  •'^  '^^  '''"'•^=  (')  ^'''her  numerous,  the 
terminal  walls  thin  and  entire ;  the  upper  and  lower  walls  rather  thick 
and  very  coarsely  pitted  ;  the  lateral  walls  with  variously  oval,  oblong, 

mer'wooH  '.  ^^.'k'  '"ll  "^"'''^  ^'  ^'  *^=''=*'^''*'  becoming  2  in  'the  sum^ 
mer  wood ;  (2)  the  cells  equal  to  about  5  spring  tracheids,  the  terminal 

Mi«         if      '^T'^  ;  the  upper  and  lower  walls  thin  and  entire  ;  the 

lateral  walls  with  oval,  oblong,  or  round  pits,  2-4,  chiefly  4,  pe^  tra- 

cheid,  becoming  2  in   the  summer  wood.    Bordered  pits   in   i   row 

sometimes  in  pairs,  often  numerous,  elliptical.    Pits  on  the  tangential 

walls  of  the  summer  wood  wholly  wanting. 


330  ANATOMY  OF  THE  GYMNOSPERMS 

TaHi'tnlial.  Fusiform  rayn  rather  numerous  and  narrow,  the  terminals 
somewhat  prolonKcd  but  rather  broad,  the  cells  of  the  inflated  portion 
rather  thick-walled,  those  of  the  terminals  lar;"  and  thin-wallccl. 
Ordinary  rays  rather  numerous,  low  to  medium,  much  narrowed  l.y 
the  numerous  and  very  variable,  interspersed,  and  predominant  tra 
cheids;  the  relatively  few  parenchyma  cells  often  resinous,  very 
unequal  and  variable,  oval,  both  thick-  and  thin-walled,  the  latter 
often  much  broken  out. 

A  large  tree  61-91  m.  high,  with  a  trunk  3.60-4.57  m.  in  diameter. 
Wood  variable  in  quality  and  value,  hard,  heavy,  strong,  brittle,  not  coarse 
grained  nor  durable,  compact. 

Specific  gravity 0-4715 

Percentage  of  ash  residue °-35 

Approximate  relative  fuel  value ^^° 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  824- 

Ultimate  transverse  strength  in  kilograms       279' 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  6292. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms       .     .  1740. 

(Sargent) 
Interior  of  British  Columbia  south  of  latitude  51",  thence  southward  along 
the  mountain  ranges  of  the  Paci'ic  region  to  Mexico ;  eastward  to  liie 
Black  HilLs  of  Dakota,  Colorado,  and  western  Texas.  Dry,  rocky  ridKcs 
and  prairies,  or  in  the  northern  portion  of  California,  rarely  in  cold,  wet 
swamps,  reaching  its  greatest  development  on  the  western  slopes  of  the 
California  Sierras  (Sargent). 

27.   P.  Coulttri,  D.  Don 
Pitch  Pint 

Tranmtrse.  Growth  rings  thick,  variable.  Summer  wood  thin,  upwards  of 
10  tracheids  and  open,  the  transition  gradual ;  the  tracheids  very-  vari- 
able, inded,  and  often  much  compressed,  in  conspicuously  irregular 
row;  pring  tracheids  large,  squarish-hexagonal,  the  walls  ratlier 
thi:  Xesin  passages  rather  abundant,  medium;  the  epithelium  in 
1-  ■■■■:  eral  rows  of  large,  rather  thick-walled,  and  chiefly  rounded  cells, 
no.  csinous,  often  forming  extensive  and  irregular  tracts  about  tlie 
canal.  Medullary  rays  broad,  i  cell  wide,  rather  prominent,  distant 
2-20  rows  of  tracheids. 

fiAdial.  Rays  sparingly  resinous  throughout ;  the  tracheids  low,  often  pre- 
dominant, nwre  or  less  reticulated  throughout,  and  often  composing 
the  entire  structure  in  low  rays.  Parenchyma  cells  fusiform,  of  two 
kinds:  (i)  high  and  prominent,  especially  in  the  low  rays;  the  ter- 
minal walls  thin  and  not  pitted;  the  upper  and  lower  walls  thick  and 
coarsely  pitted ;  the  lateral  walls  with  round  or  oval  and  prominent  pits, 
1-4,  more  rarely  6,  per  tracheid,  becoming  1-2  in  the  summer  wood; 
and  (2)  the  cells  fusiform,  the  terminal  walls  thin  and  not  pitted ;  the 
upper  and  lower  walls  very  thin,  often  much  broken  out,  or  auun 


PINUS  33, 

ateral  wa  I,  w.th  oval  or  lenticular  pitn.  ,-3.  chicflv  2.  per  trachei.l 
.hrouKhout.  very  unequal  and  variable  in  form  ancf  siie  Ikirdert-.l 
pits  in  I  row.  sometimes  in  pair»,  elliptical.  InJcominR  greatly  re- 
duced in  the  Kummer  wood,  and  fin^giy  wantinK,  J'itn  on  the  tanRent  .1 
walls  of  the  summer  wood  wholly  wanting  lanKenii.u 

langeHhal.  Fusiform  rays  rather  numerous,  medium,  narrow  ;  the  acute  or 

«NTSriffl,/T'"^''"  "''""'' T*'""'''^""'^^^  °f  tracheidn;  the 
cells  of  the  inflated  portior  vtry  thin-walled  and  usually  broken  out 
Ordinary  rays  rather  numerous,  low  to  high,  nonresinous  and  presentini,' 

l„H^Kf''^""'^f'/"'^'^'''L  <■>'*'*  ">"  *»'°"y  ^"mposed  of  tracheidt 
and  thick-walled  parenchyma  cells,  rarely  2-^riate    at  least  in  part; 

m.lh  T  I  rays  w„h, he  thin-walled  parenchyma  of  the  central  portion 
much  broken  out.  and  showing  an  interspersed  thick-walled  paren- 
tlwlln  r"  •*"=  ""''^^!  »"d  (3)  .-seriate  rays  chiefly  composed 
of  hin-walled  parenchyma  terminated  above  and  below  by  thick-walled 
cells  and  tracneids. 

tl^u^:f^  "I:  '*'*''*'•  *"''  "."■""*'  upwards  of  1.80  m.  in  diameter. 
Wood  light,  soft,  not  strong,  brittle,  and  coarse  grained. 

Specific  gravity 

Percentage  of  ash  residue    ......  o  t?^^ 

Approximate  relative  fuel  value    .     .     .     .     .  '     '        4,,8 

Coefficient  of  elasticity  in  kilograms  on  miilim'eter;,            "  lui" 

Ultimata  transverse  strength  in  kilograms  .  ,,/ 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  587a 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  ^A^T 

(Sargent)                                                                           "  ^"' 

The  Coast  Range  of  California,  most  abundant  and  attaining  its  greatest 
development  in  the  San  Jacinto  Mountains  (Sargent). 


s 


i 


28.  P.  tuberailau,  Gord. 

KiiohCone  Pine 

Transverse.  Growth  rings  thick.  Summer  wood  prominent,  open,  upwards 
of  equal  to  the  spring  wood  ;  the  tracheids  very  unequal  in  regular 
rows,  distinctly  rounded,  or  the  outermost  more  or  less  compressed 
and  with  much  thmner  walls ;  the  transition  from  the  spring  wood 
gradual.  Spring  tracheids  hexagonal,  .somewhat  variable,  in  regular 
rows,  the  walls  thin.  Resin  passages  rather  numerous,  chiefly  in  the 
summer  wood,  scattering,  large  ;  the  epithelium  in  1-3  rows  of  large 
and  very  thin-walled  and  resinous  cells  which  form  a  more  or  less 
extended  tract  and  often  merge  into  thitker-walled  parenchyma  or  thin- 
walled  tracheids.  Medullary  rays  rather  broad.  1  cell  widt-,  not  prom- 
ment,  sparingly  and  locally  resinous,  di.stant  2-15  rows  of  tracheids. 

Kadtal.  Rays  .sparingly  and  locally  resinous,  the  resin  ma.ssivc  ;  the  ray 
tracheids  about  equal  to  the  parenchyma  cells,  sometimes  predominant 
and  interspersed,  the  upper  and  lower  walls  dentate,  more  or  less 
reticulated  throughout.    Ray   cells  of  two  kinds:  (1)  thick-walled 


ft 


332  ANATOMY  OF  THK  (IVMNOSPKRMS 

nomcwhat  (usiform  cells  chiefly  c(iii<incd  to  the  low  ray«  and  noitic 
what  rar«r;  the  leiminal  vi alls  thin  .md  locally  thickened ;  the  upiJ<-. 
and  lovkcr  waIN  thirk  and  .ttmnuly  pitted  ;  the  lateral  wall*  with  round 
or  lenticular  and  usually  simple,  rarely  Vjordtrcd  pits,  3-4  per  tracheiil . 
and  (2)  fusiform  cells,  with  the  terminal,  upper,  and  lower  walls  very 
thin  and  usually  much  broken  out;  the  latiral  wall»  with  variously 
lenticular,  round  or  oval  pits,  2  4,  chiefly  4.  per  tracheid,  in  the  sum- 
mer wood  reduced  t«  2,  and  rtnally  to  1,  and  becominK  very  narrow 
and  much-prolonKcd  siil».  Hordered  pits  in  1  row,  sometimes  in  pair*, 
elliptical.  Fit*  on  the  tangential  walls  of  the  summer  wood  wholly 
wanting. 
Tant;ential.  Fusiform  rays  not  numerous,  medium  to  low,  narrow,  very 
unsymmetri>  li,  the  terminals  chiefly  acute,  rarely  somewhat  prolonged  : 
the  intlated  portion  wholly  compo.scd  of  very  thin-walled  cells  which 
are  commonly  broken  out.  Ordinary  rays  medium,  rather  numerous 
and  vcrv  broiid,  pres*  iitinK  three  principal  aspects:  (i)  low  rays  wholly 
composed  of  terminal  tracheids  and  ihin-walleil.  resinous  parenchyma 
comninnly  broken  out ;  (2)  higher  rays  composed  of  very  thin-wali'd, 
resinnwi.s  piirenchyma  much  broken  out,  with  terminal,  interspers.  4 
and  predominant,  small  tracheids  which  cause  local  contraction  ;  aiul 
(3)  low  rays  composed  of  tracheids  with  I  centra!,  thick-walled  paren- 
chyma cell. 

A  tree  18-22  m.  hi>{h,  with  a  trunk  upwards  of  .90  m.  m  diameter. 
Wood  light,  .soft,  not  strong,  brittle,  coarse  grained,  and  compact. 

Specific  gravity .     •  <3-3499 

Perccnta^'e  of  ash  residue .     .  0.33 

Approximate  relative  fuel  value               34**''* 

Coefficient  i>f  elasticity  in  kilograms  "n  millimelcf       .  429. 

Uliimate  transverse  strens{ih  in  kilogiams 175 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  4207. 

Resistance  to  indentation  to  I. .;7  mm.  in  kilograms      .     .  1372- 
(Sargent) 

Dry,  gravelly  ridges  and  slopes,  not  lom  ion,  2500-5000  feet  eleva- 
tion. Valley  of  the  Mackenzie  River.  Ore);>'ii.  and  southward  alonir  the 
slopes  of  the  Cascade  and  Sierra  N  cvada  mountains,  and  in  the  California 
Coast  Range  from  Santa  Cruz  to  the  San  Jacinto  Mountains  (Sargent). 


29.   P.  TotreytUft,  Torr. 

SoltiltiJ  Pint 

Transverse.  Growth  rings  variable,  tfie  structure  showing  a  marked  tend- 
ency to  radi.il  fracture.  Summer  wood  prominent  but  rather  optn, 
about  one  :hird  the  spring  wood,  (torn  which  the  transition  is  aluLpl 
when  thin,  ut  when  thicker  the  transitibn  is  often  gradual  both  v  !\s; 
the  tracheids  large,  squarish,  and  often  in  irregul.i.  row  ■<.  prmg 
tracheids  large,  squari^  rather  uniform  in  regular  rows,  the  ".ills 
medium.  Resin  passages  scattering,  median:  ;  the  epithelium  ci'm- 
posed  of  larK'  ■  thin-walled,  irregular  and  resinous  ceils  in  1-3  rows, 


PINUS  333 

r£Mn',H  '"n  ''"^If  ..*""'  ■*"*'  ""'^s^lly  l>»"  inlo  occasional 
K' Hut  ."  •  "«*"'  "y  '»>"  broad.  ,  cell  wide.  m,.  very  prom- 
inent,  distant  2-10  rows  of  trachcid.1. 

Radial.  Ray>  .paringly  resinous,  the  resin  confined  to  the  thin  walls  •  ihe 
iracheid.  about  equal  to.  or  in  the  low  rays  exceeding,  the  pare  "chym! 
cell.;  rarely  interspersed.  MronKlv  reticulated  throughout     SccH^^'s 

walls  thin  and  entire  ;  the  upper  and  lower  walls  thick  c«  .rs^lv  Ind 

Imperfectly  p  tted  ,  the  lateral  walls  with  very  prominen    and  mund 

elliptical  or  oblong  pits  which  sometimes  lK.cnn,e  distinclirilrdrnd 

n    he  summer  w«>«d,  2-4,  chierty  4,  per  tracheid  ,  and  (2)  celN      oid 

Ind  m?;h*I!'*  r*''".'"^"  '  "'V'^^'"'""''  "P»^'-  and'lower  w   Is  very  "hi* 

n  paTrs  TlK'  al'in^.hJ'"'''''    "°1""*  P""  '"  '  --    -"'clme: 
i^c     n      P        •  '"  "^*  summer  wood  quickly  reduced  to  1-.-IJ  .. 

rhoif;  waVt;;^:^  "■  ^'" "-  "^^  '»"«-"'•  -"^ «'  '•'^-  ---  :t(s 

TaHgtHtiai.  Fusiform  rays  rather  numerous.  s,nall  to  mer'ium.  the  (.rminals 

herJh't.'Vh^^  •':?'"7'-:'  '"'°"«^*''  "^"^■"  "«»'«'  fo  .he  "hole 
height ;  th.-  tells  of  ,he  terminals  compc.a-,i  of  thick-walitd  r.aren 
chymaand  small  a.  (.ids.  those  of  the  inriated  |K,rtion  v.ry  mm- 
waled  and  generally  t,roken  out.  Ordinary  rays  low  "o  mediu 
somewhat  numero.  broad,  very  r;K.ly  contracted  by  the  smaM  and 
r:  uch  narrower,  mtcrspersed  tracl>.  kIs  of  the  highest  rays  hk 
*  ailed  parenchyma  cells  few  ,  thin-walled  parenchyma  oHs  predon  ■" 
injr  t.  resinous,  much  broken  ou^  jjicuum 

A  low,  .^ort-lived,  gnaric  :,  and  cro...cd  tree  6-8  m.  hi^h,  «i,h  a  trunk 
upwards  of  .33  m.  in  diameter. 

Wood  light,  soft,  not  strong,  britti,  .  ra.ne.  clo.se  grained,  and  comp.ict. 
Specific  gravity       ... 
Percentage  of  a.sl    residu.     ..."  0-4879 

Approximate  rtla    .e  fuel  value °f ' 

Coefficient  of  cla>L.ity  in  kilogram.s      t  miliinuurs'     .'     '       A°' '' 
t.    mate  transvers.   Mrength  in  kilograms  .  ,;; 

ulS"    '''•■*""'^'-"  '°  '■   '<itudinal  cru.shinK  in  kilograms     A'A 

RcMstan.     to  „.dentat        to  1.27  mm.  in  kilogran  .,00 

(Sar^:  nt)  **  •     -3°*J- 

Aserylocal  tre.   ,      San         i;o  County,  California,  and  possibly  Lower 
Cilifornia  and    he  island.-,  off  Santa  Barbara  (Sargent;. 

30.   P.  chihiuthiuma,  Kngclm. 

Tram    -rs-      Gro.th  rings  thin,  variable.     Summer  wood    'hin,  variable 

1-     H,,.,ker  zones  dense,  the  thin  zones  open  ;  the  tran    ; ion  from  thj 

H>"nz  wood  rather  aljrupt ;  the  tracheids  in  regular  n..,    variable 

bprn  ,    tracheids  squarish-hexagonal,  very  uncj^al  in  reg^Iarrows' 


IK' 


■'i'- 


334  ANATOMY  OF  THE  GYMNOSPERMS 

the  walls  rather  thin.  Resin  passages  very  round,  large,  somewhat 
numerous ;  the  epithelium  cells  at  first  flattened  and  rather  thin-walled, 
quickly  passing  into  large,  rounded,  thick-walled,  and  strongly  resinous 
wood-parenchyma  cells  which  often  form  extensive  and  somewhat 
irregular  tracts.  Medullary  rays  prominent,  resinous,  broad,  i  cell 
wide,  distant  2-10  rows  of  tracheids. 

Radial.  Rays  locally  and  strongly  resinous,  the  resin  massive ;  the  ray 
tracheids  low,  marginal,  and  interspersed,  often  predominant,  strongly 
dentate  and  sparingly  reticulated  in  the  summer  wood.  Ray  cells  of 
two  kinds,  but  merging  and  not  always  -learly  distinguishable:  (1) 
thick-walled,  fusiform  cells ;  the  terminal  walls  thin  and  locally  thick- 
ened ;  the  upper  and  lower  walls  coarsely  pitted ;  the  lateral  walls 
with  very  variable,  oval,  or  lenticular  pits,  2-4,  chiefly  3,  per  tracheid, 
becoming  1  in  the  summer  wood ;  and  (2)  thin-walled,  fusiform  cells ; 
the  terminal,  upper,  and  lower  walls  thin  and  not  pitted,  the  former 
often  locally  thickened  ;  the  lateral  walls  with  lenticular,  chiefly  narrow 
and  simple  pits,  2-4  per  tracheid,  becoming  1-2  in  the  summer  wood. 
Bordered  pits  in  1  row,  sometines  in  pairs,  elliptical,  becoming  smaller 
toward  the  summer  wood,  where  they  are  finally  obscure.  Pits  on  the 
tangential  walls  of  the  summer  wood  wholly  wanting. 

Tangential.  Fusiform  rays  rather  numerous,  low,  variable,  rather  broad 
and  unsymmetrical ;  the  terminals  acute  or  prolonged  ;  the  cells  vari- 
able, chiefly  thick-walled  throughout,  often  resinous.  Ordinary  rays 
low,  numerous,  resinous,  and  strongly  contracted  by  the  frequently 
interspersed  and  much  narrower  tracheids ;  the  parenchyma  cells  of 
two  kinds:  (i)  thick-walled  cells  chiefly  predominant;  and  (2)  thin- 
walled  cells  more  or  less  broken  out,  interspersed. 

A  small  tree  18-24  m.  high,  with  a  trunk  upwards  of  .4S-.60  m.  in  diameter 
Wood  light,  soft,  strong,  brittle,  close  grained,  and  compact. 

Specific  gravity 0.5457 

Percentage  of  ash  residue 0.39 

Approximate  relative  fuel  value 54-37 

Coefficient  of  elasticity  in  kilograms  on  millimeters      .     .  726. 

Ultimate  transverse  strength  in  kilograms 355. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  5398. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms      .     .  2470. 
(Sargent) 

Dry,  rocky  ridges  and   slopes   between    5000    and   7000    feet   elevation 
Arizona,  New  Mexico,  and  Chihuahua,  Mexico,  not  common  (Sargent). 


31.   P.  Jeffre]rl>  A.  Murr. 

Hull  Pine.    Bla(k  Pine 

Transverse.  Growth  rings  narrow,  rather  uniform.  Summer  wood  tliin 
and  open,  or  again  very  thin  and  very  open  ;  the  tracheids  uniform  in 
regular  rows,  more  rarely  unequal  in  irregular  rows  ;  the  transition  from 
the  spring  wood  rather  gradual.    Spring  tracheids  large,  hexagonal, 


PINUS  335 

very  unequal  in  regular  rows,  the  walls  rather  thin.  Resin  passaees 
large,  scattering;  the  epithelium  composed  of  very  large,  rounded, 
rather  thin-walled  and  variable  cells  in  1-3  rows,  often  forming  rather 
large  tracU.  Medullary  rays  broad,  i  cell  wide,  not  very  prominent, 
distant  2-i6  rows  of  tracheids. 

Radial.  Rays  nonresinous ;  the  tracheids  strongly  dentate  and  more  or  less 
reticulated  throughout,  numerous  and  strongly  predominant  Ray 
cells  of  two  kinds:  (1)  thick-walled  cells  prominent,  fusiform,  equal 
to  about  s  spnng  tracheids  ;  the  terminal  walls  locally  thickened  -the 
upper  and  lower  walls  strongly  thickened  and  pitted ;  the  lateral  walls 
with  prominent,  round  pits,  2-5,  chiefly  3-4,  per  tracheid,  conter- 
minous with  and  merging  into  the  cells  of  the  second  order;  and 
(2)  fusiform  cells  equal  to  about  5  spring  tracheids;  the  terminal 
walls  thin  and  not  locally  thickened  ;  the  upper  and  lower  walls  thin 
and  entire  or  more  rarely  locally  thickened;  the  lateral  walls  with 
lenticular  or  oval,  very  variable  pits,  1-4  per  tracheid.  Bordered  pits 
in  I  row,  sometimes  in  pairs,  elliptical,  becoming  quickly  reduced  in 
the  summer  wood,  and  finally  7.2  /*.  Pits  on  the  tangential  walls  of 
the  summer  wood  wholly  wanting. 

Tangential.  Fusiform  rays  few,  medium,  the  terminals  acute  or  somewhat 
prolonged;  the  cells  of  the  inflated  portion  large  and  thin-walled, 
usually  much  broken  out.  Ordinary  rays  rather  numerous,  medium  to 
high,  nonresinous,  chiefly  composed  of  narrow  tracheids  with  inter- 
spersed and  much  broader  parenchyma  cells.  Parenchyma  cells  of  two 
kinds:  (1)  thick-walled  cells  which  predominate  in  low  rays,  becoming 
interspersed  in  high  rays ;  and  (2)  the  usually  broader,  more  squarish, 
and  thin-walled  cells. 

A  large  tree  30-31  m.  high,  with  a  trunk  upwards  of  4  m.  in  diameter. 
Wood  light,  strong,  hard,  rather  coarse  grained,  and  compact. 

Specific  gravity       0.5206 

Percentage  of  ash  residue o  26 

Approximate  relative  fuel  value .    .     .  eoiss 

Coefficient  of  elasticity  in  kilograms  on  millimeters  .     '.     '.  925! 

Ultimate  transverse  strength  in  kilograms 318. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  6679! 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  .     .     .     1850. 
(Sargent) 

Drj-,  gravelly  slopes  between  6000  and  8000  feet  elevation.  Along  the 
Sierra  Nevadas  of  California  from  Siskiyou  Mountains  to  the  San  Ber- 
nardino and  San  Jacinto  mountains  (Sargent). 

32.  P.  ponderosa,  Lawson 

y*/low  Pint.     Bull  Pine 

Transverse.  Growth  rings  thin,  variable.  Summer  wood  variable,  dense, 
sometimes  open,  the  transition  from  th.  spring  wood  often  abrupt;  the 
tracheids  round-hexagonal,  unequal,  and  in  somewhat  irregular  rows. 


336  ANATOMY  OF  THE  GYMNOSPERMS 

Spring  tracheids  squarish-hexagonal,  variable,  in  somewhat  regular  rows, 
rather  thick-walled.  Resin  passages  medium,  numerous,  chiefly  in  the 
summer  wood ;  the  epithelium  in  1-3  rows  of  rather  large  and  verj- 
thin-walled  cells,  succeeded  by  thick-walled  elements,  the  whole  forming 
a  somewhat  extended  tract  which  commonly  breaks  out  in  making  tran.s- 
vers«:  sections.  Medullary  rays  very  broad,  i  cell  wide,  nonresinous, 
not  numerous,  distant  2-15,  or  sometimes  20  rows  of  tracheids. 

Radial.  Kays  nonresinous ;  the  tracheids  predominant  or  equal  to  the  paren- 
chyma cells,  and  usually  strongly  reticulated.  Parenchyma  cells  of  two 
kinds :  ( I )  rather  few ;  the  terminal  walls  thin  and  locally  thickened ; 
the  upper  aaJ  lower  walls  rather  thick  hut  not  very  strongly  pitted ; 
the  lateral  walls  with  very  conspicuous,  tound  or  lenticular,  very  vari- 
able pits,  2-4,  rarely  5,  per  tracheid ;  and  (2)  variously  contracted  cells, 
the  terminal,  upper,  and  lower  walls  thin  and  entire ;  the  lateral  walls 
with  lenticular  or  oval  pits,  1-4  per  tracheid.  Bordered  pits  in  i  row, 
round  or  more  generally  elliptical.  Pits  on  the  tangential  walls  of  the 
summer  wood  wholly  wanting. 

Tangential.  Fusiform  rays  somewhat  numerous,  low  to  medium ;  the  termi- 
nals acute,  composed  wholly  of  tracheids ;  the  cells  of  the  inflated  por- 
tion very  thin-walled  and  usually  broken  out.  Ordinary  rays  low, 
numerous,  nonresinous;  the  tracheids  chiefly  terminal  or  when  inter- 
spersed causing  a  slight  contraction  ;  the  thick-walled  parenchyma  cells 
chiefly  termini,  few,  the  thin-walled  parenchyma  occupying  the  central 
region  and  forming  the  greater  portion  of  the  ray,  generally  broken  out, 
the  cells  oval,  variable. 

A  large  tree  61-91  ™-  >"  height,  with  a  trunk  upwards  of  4.57  m.  in 

diameter. 
Wood  varying  greatly  in  quality  and  value,  heavy,  hard,  strong,  brittle,  not 

coarse  grained  or  durable,  compact. 

Specific  gravity 0.4715 

Percentage  of  ash  residue 0.35 

Approximate  relative  fuel  value 46.99 

Coefficient  of  elasticity  in  kilograms  on  millimeters  .     .     .  887. 

Ultimate  transverse  strength  in  kilograms 307. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  6037. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  .     .     .  17 19. 
(Sargent) 

Interior  of  British  Columbia  south  of  latitude  5 1°,  south  and  east  along  the 
mountains  of  the  Pacific  region  to  Mexico,  the  Black  Hills  of  Dakota, 
Colorado,  and  western  Texas.  Dry,  rocky  ridges;  rarely  in  cold,  wet 
swamps,  reaching  its  greatest  development  on  the  western  slope  of  tlie 
California  Sierras.  After  Pseudotsuga  Douglasii,  the  most  generally  dis- 
tributed and  most  valuable  timber  tree  of  the  Pacific  forests  (Sargent). 
The  distribution  of  this  species  and  the  qualities  of  the  wocJ  are  not 
clearly  separable  from  the  next  species. 


PINUS 


33- 


33.  P.  Bcopakmim,  Lemmon 

^''"'i^^rse  Summtr  wood  very  variable,  rather  open,  commonly  double: 
the  tracheids  m  very  regular  rows  and  uniform,  but  generaUy  much  com- 
pressed;  the  transition  from  the  spring  wood  rather  abrupt.  Sprine 
tracheids  conspicuously  squarish,  rather  uniform  in  regular  rows,  lard 
and  thin-walled  Resin  passages  rather  numerous  and  scattering  not 
large ;  the  epithelium  nonresinous,  composed  of  about  2  rows  of  verv 
large  and  very  thin-walled  ceUs,  those  of  the  limiting  layer  flattened 
r5!!f/i  'f*=°"*^*T,  l»y««  "-ound,  merging  into  a  few  thick-walied! 
round  parenchyina  cells  on  the  borders  of  the  wood  tracheids     Medul' 

Sllf/,'  ?    "  ^'°'^'  /  ""  ''**'*'■  '''•'"  """""""^  but  not  prominent, 
distant  2-10,  more  rarely  1 7,  rows  of  tracheids. 

Hadia^  Rays  nonresinous ;  the  ray  tracheids  commonly  high,  marginal,  or 
r^tirZ^n'^TP*^"^,*^  '^  "^^  "J'-S*""  "^y'-  P-^dominant  knd  sparingly 
locally  thickened  ;  the  upper  and  lower  walls  thick  and  strongly  pitted  ; 
the  lateral  walls  with  round,  simple  pits  1-4  per  tracheid,  conteminous 
and  interspersed  with  those  of  the  second  order;  and  (2)  the  terminal 
upper  and  lower  walls  thin  and  not  pitted  or  locally  thickened ;  the 
hiteral  walls  with  small,  lenticular  pit.s,  2-4,  chiefly  4,  per  tracheid, 
becoming  i  or  2  in  the  summer  wood.  Bordered  pits  in  i  row 
numerous,  crowded,  elliptical.  Pits  on  the  tangential  walls  of  the 
summer  wood  wholly  wanting. 

Tangential.  Fusiform  rays  not  numerous,  narrow  ;  the  somewhat  prolonged 
terminals  composed  of  tracheids ;  the  inflated  portion  composed  of  v^r>- 
thm-walled  cells,  usually  all  broken  out.  Ordinary  rays  rather  numerous^ 
low  to  medium,  nonresinous,  conspicuously  contracted  by  the  somewhat 
narrower,  sometimes  interspersed,  and  conspicuously  predominant  tra- 
cheids; the  thick-walled  parenchy-ma  cells  few,  not  prominent,  the  thin- 
waued  parenchyma  cells  occupying  the  central  tract,  oval,  variable. 

34.  P.  pungens,  Michx.  f. 

Table  Mountain  Pint.     Hickory  Pint 

Transverse.  Growth  rings  thick.  Summer  wood  ver>-  prominent,  dense  or 
sometimes  somewhat  open,  often  double,  the  transition  from  the  spring 
wood  gradual,  sometimes  abrupt ;  the  tracheids  in  regular  rows,  vari- 
able, rounded.  Spring  tracheids  strongly  hexagonal,  verv-  unequal  in 
regular  rows,  the  walls  rather  thick.  Resin  passages  rather  large, 
numerous,  chiefly  in  the  summer  wood;  the  epithelium  in  i  row  of 
veiy  thm-walled  and  nonresinous  cells,  rarely  much  exceeding  the  canal 
and  forming  eccentric  tracts  of  limited  extent.  Medullary  rays  rather 
it.  V  /  o'  ^""^what  prominent,  numerou.s,  distant  2-15  rows  of  tracheids 
Kadtal.  Rays  somewhat  resinous  throughout ;  the  tracheids  variable,  often 
predominant,  reticvlated  tliroughout  and  more  or  less  interspersed 
Ray  cells  of  two  kind.> :  ( i )  cells  numerous  and  long  fusiform  ;  the  ter- 
minal walls  entire  or  locally  thickened  :  the  upper  and  lower  walls 
strongly  thickened  and  coarsely  pitted  ;  the  lateral  walls  with  very  vari- 
able, oval,  or  lenticular  pits,  1-3  per  tracheid,  in  the  summer  wood 
distincUy  bordered,  the  orifice  a  prolonged  slit ;  and  (2)  cells  variously 


w 


'■ 


M  y 


f 

\  M&l 

1 

338  ANATOMY  OF  THE  GYMNOSPERMS 

fusiform,  the  terminal,  upper,  and  lower  walls  thin  and  usually  much 
broken  out;  the  lateral  walls  with  lenticular  or  oval,  very  variable 
pits,  1-4,  chiefly  2  or  3,  per  tracheid,  in  the  summer  wood  becoming 
distinctly  bordered,  the  orifice  an  extended  slit,  conterminous  with 
tracheids  and  cells  of  the  first  order.  Bordered  pits  in  I  row  or  pairs, 
elliptical,  and  toward  the  summer  wood  soon  replaced  by  narrow  slits, 
which  often  lead  into  strong,  double  striations.  Pits  on  the  tangential 
walls  of  the  summer  wood  wholly  wanting. 
Tangential.  Fusiform  rays  not  numerous,  low  and  broad,  the  chiefly  acute 
terminals  composed  of  a  few  tracheids ;  the  cells  of  the  inflated  portion 
very  thin-walled,  chiefly  broken  out,  or  again  rather  thick-walled  in  part 
and  pwrsistent.  Ordinary  rays  low  to  medium  and  presenting  four  prin- 
cipal aspects :  ( I )  low  rays  of  thin-walled  parenchyma,  much  broken  out, 
and  small,  terminal  tracheids ;  (2)  low  rays  of  thick-walled  parenchyma 
and  small,  terminal  tracheids ;  (3)  higher  rays  of  thick-walled  paren- 
chyma and  both  terminal  and  interspersed  tracheids  with  occasional 
thin-walled  parenchyma;  and  (4)  the  highest  rays  of  thin-walled,  resin- 
ous, and  interspersed  thick-walled  parenchyma,  together  with  terminal 
and  interspersed  tracheids. 

A  tree  9-18  m.  high,  with  a  trunk  upwards  of  t.05  m.  in  diameter. 
Wood  light,  soft,  not  strong,  brittle,  coarse  grained,  and  compact. 

Specific  gravity 0-4935 

Percentage  of  ash  residue 0.27 

Approximate  relative  fuel  value 49-22 

Coefficient  of  elasticity  in  kilograms  on  millimeters        .     .  803. 

jltimate  tran.sverse  strength  in  kilograms 310. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  5670. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  .     .     .  1842. 
(Sargent) 

Allegheny  Mountains,  Pennsylvania  to  Tennessee,  in  the  high  moimtains  of 
the  latter  attaining  its  greatest  development  (Sargent). 


35.  P.  inops,  Ait. 

Jersey  Pine.     Scrub  Pine 

Transverse.  Growth  rings  thick,  often  double.  Summer  wood  rather  dense, 
sometimes  more  or  less  open,  equal  to  about  one  fourth  or  one  third  the 
spring  wood,  from  which  the  transition  is  usually  abrupt ;  the  tracheids 
strongly  unequal,  chiefly  in  regular  rows.  Spring  tracheids  squarish, 
large,  very  uniform  in  regular  rows,  the  walls  thin.  Resin  passajjes 
rather  numerous,  medium;  the  epithelium  in  1-2  rows  of  large,  round, 
thin-walled  or  again  rather  thick-walled,  resinous  cells,  which  are  often 
developed  eccentrically  about  the  canal,  and  become  thicker-walled 
especially  on  the  outer  limits.  Medullary  rays  prominent,  rather  broad, 
I  cell  wide,  not  numerous,  distant  2-12  rows  of  tracheids 

Radial.  Rays  somewhat  resinous,  the  resin  massive,  localized ;  the  tracheids 
numerous  low,  very  variable  and  verj'  strongly  reticulated  throughout, 
predominant,  often.interspersed.  Ray  cells  of  two  kinds  :  ( i )  the  terminal 


PINLS  339 

walls  thin  and  locally  thickened;  the  upper  and  lower  walls  more  or 
less  thickened  and  coarsely  pitted ;  the  lateral  walls  with  lenticular 
or  oval,  variable  pits,  2-6  chiefly  4,  per  tracheid,  finally  becoming  slit- 
like and  reduced  to  i  in  the  summer  wood  or  eventually  obsolete,  often 
conterminous  with  tracheids  or  with  thin-walled  parenchyma  cells:  and 
(2)  the  predominant  elements ;  the  terminal,  upper,  and  lower  walls  thin : 
the  ateral  w^ls  with  very  variable,  oval,  or  lenticular  pits,  1-4  or  more 
rarely  5  chiefly  4,  per  tracheid,  in  the  summer  wood  merging  into  pro 
lonpd  shts  or  final  y  into  round,  bordered  pits  with  an  oblong,  narrow 
orifice;  fusiform,  chiefly  high.    Bordered  pits  in  i  row  or  paiw,  ellip- 
tical, becoming  round  and  conspicuously  smaller  toward  the  silmmer 
wood,  where  they  are  finally  reduced  to  72  ^.    Pits  on  the  tangential 
walls  of  the  summer  wood  wholly  wanting. 
Tangential.  Fusiform  rays  medium,  rather  few,  narrow ;  the  terminals  acute 
and  composed  of  large  and  small  tracheids;  the  inflated  portion  com- 
posed of  thin-walled  tissue,  much  broken  out  and  more  or  less  resinou.s 
Ordinary  rays  chiefly  low  and  presenting  three  principal  aspects-  f  1) 
low  rays  distincdy  fusiform,  with  a  large  tracheid  in  the  center  and 
small  terminal  tracheids;  (2)  higher  rays  of  i-several  large,  thin-walled, 
and  resinous  cells,  much  broken  out,  with  or  without  interspersed  thick- 
walled  cells,  sometimes  in  pairs,  and  terminal  tracheids  of  variable 
size;  and  (3)  the  highest  rays  composed  of  large,  thin-walled  paren- 
chyma cells,  often  with  resin,  but  usually  much  broken  out,  terminal 
tracheids  and   i-several  small,  interspersed  tracheids,  causing  local 
contractions.  * 

A  tree  24-36  m.  high,  with  a  trunk  upwards  of  .90  m.  in  diameter. 

Wood  light,  soft,  not  strong,  britUe,  very  close  grained,  compact,  and  durable. 

Specific  gravity ^ 

Percentage  of  ash  residue '  o'w 

Approximate  relative  fuel  value      .......'  52  q» 

Coeflicient  of  ela.sticity  in  kilograms  on  millimeters  '.     '     '  cL 

Ultimate  transverse  strength  in  kilograms   ....  281 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  5765 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  .     .  2406' 

(Sargent)  ^^' 

Sandy,  generally  barren  soil.  Long  and  Staten  islands.  New  York ;  south- 
ward usually  near  the  coast  to  South  Carolina  and  westward  through 
eastern  and  middle  Kentucky  to  southeastern  Indiana  (Sargent). 

86.  P.  mur  Jita,  D.  Don 

I'lkkle-Couc  /'hie 

Transverse.  Growth  rings  thick.  Summer  wood  prominent  but  rather  thin 
about  one  fifth  the  spring  wood,  variable,  both  dense  and  open  •  the 
tracheids  variable,  in  the  open  zones  often  much  compressed  and  in 
irregular  rows,  the  walls  variable ;  the  transition  from  the  spring  wo,)d 
rather  gradual.    Spring  tracheids  hexagonal,  unequal,  in  regular  rows 


!    1 


n 


^\ 


1 

A,. 


340  ANATOMY  OF  THE  GYMNOSPERMS 

the  walls  rather  thin.  Resin  passages  scattering,  rather  small,  somewhat 
numerous,  chiefly  in  the  summer  wood;  the  epithelium  in  1-2  rows  of 
large,  rounded,  ':hin-walled,  often  strongly  resinous  cells,  which  some- 
times become  thick-walled  at  the  outer  limits.  Medullary  rays  not 
numerous  or  prominent,  rather  narrow,  i  cell  wide,  distant  2-30  rows 
of  tracheids. 

Radial.  Rays  locally  somewhat  resinous,  the  resin  massive;  the  ray  tra- 
cheids strongly  predominant,  often  composing  the  entire  structure  of  the 
low  rays,  in  the  higher  rays  marginal,  more  rarely  interspersed,  reticulated 
in  the  summer  wood.  Ray  cells  of  two  kinds : '  (i)  rather  frequent  but 
not  predominant  except  in  the  low  rays,  rather  high  and  long  fusiform ; 
the  terminal  walls  thin,  sometimes  strongly  pitted ;  the  upper  and  lower 
walls  rather  thick  and  coarsely  pitted ;  the  lateral  walls  with  prominent 
and  very  variable,  oval,  round,  or  lenticular  pits,  1-4  per  tracheid; 
and  (2)  cells  resinous,  the  terminal,  upper,  and  lower  walls  thin  and 
much  broken  out;  the  lateral  walls  with  lenticular  pite  1-3,  chiefly  2, 
per  tracheid.  Bordered  pits  in  i  row,  sometimes  in  pairs,  numerou.s, 
elliptical.  Pits  on  the  tangential  walls  of  the  summer  wood  wholly 
wanting. 

Tangential.  Fusiform  rays  low,  the  terminals  acute,  rarely  prolonged ;  the 
cells  of  the  inflated  portion  large  and  rather  thin-walled,  often  wholly 
broken  out.  Ordinary  rays  low,  rather  broad,  the  cells  very  variable  in 
shape  from  oval  to  squarish,  and  presenting  four  principal  aspects :  ( 1 ) 
low,  fusiform  in  shape,  composed  of  thick-walled,  oval  parenchyma  cells 
with  terminal  tracheids ;  also  higher  rays  of  the  same  a.spect ;  (2)  low 
rays  of  thick-  and  thin-walled,  oval  parenchyma  —  the  latter  resinous, 
but  otherwise  not  very  different  —  and  small,  terminal  tracheids;  (3) 
higher  rays  of  large,  broad,  thin-walled,  resinous  parenchyma,  1-2  thick- 
walled  parenchyma  cells  and  terminal  tracheids;  and  (4)  the  highest 
rays  of  thick-walled  parenchyma  and  interspersed  tracheids  with  local 
contractions.    Parenchyma  cells  oval,  very  narrow. 

A  tree  24-36  m.  high,  with  a  trunk  upwards  of  .90  m.  in  diameter. 
Wood  light,  very  strong  and  hard,  coarse  grained,  and  compact. 

Specific  gravity 0.4942 

Percentage  of  ash  residue 0.26 

Approximate  relative  fuel  value 49-29 

Coefficient  of  elasticity  in  kilograms  on  millimeters  .     .     .  1 194. 

Ultimate  transverse  strength  in  kilograms 441. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  8142. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  .     .     .  1950. 
(Sargent) 

The  coast  ranges  of  California,  reaching  its  greatest  development  in  Men- 
docino County.  Rare  and  local,  in  cold  peat  bogs  or  barren,  sandy 
gravel  below  2000  feet  elevation  (Sargent). 

'  The  distinction  between  these  two  forms  of  cells  is  not  very  clear  in  this 
species  and  is  best  expressed  by  the  terms  "  thicker  "  and  "  thinner  "  as  applicable 
to  elements  which  are  not  very  different,  or  which  merge  by  gradual  transitions. 


PINUS  3^, 

37.  P.  intignit,  Douglas 

Moiittrty  Pine 

Transverse.  Growth  rings  thick,  often  double.  Summer  wood  rather  open 
the  transition  from  the  spring  wood  very  gradual ;  the  tracheids  very 
unequal  in  more  or  less  irregular  rows,  often  strongly  compressed  radi- 
ally, bpnng  tracheids  hexagonal,  very  unequal  in  somewhat  regular 
rows,  the  walls  medium.  Resin  passages  scattering,  numerous,  rather 
large  ;  the  epithelium  in  1-3  rows  of  very  large,  round,  but  variable  and 
rather  thin-walled,  resinous  cells.  Medullary  rays  very  prominent,  broad 
I  cell  wide,  not  very  numerous,  distant  2-12,  more  rarely  21.  rows  of 
tracheids. 

Jiadial.Ka.ys  resinous,  the  resin  localized,  granular,  more  rarely  massive 
or  m  the  cell  wall ;  the  ray  tracheids  sparingly  reticulated  and  sparinjfly 
predominant,  when  interspersed,  very  low  and  unequal.  Ray  cells  of 
two  kinds:  (i)  cells  usually  low  and  prominent,  especially  in  the  low 
rays ;  the  terminal  walls  often  thick  and  coarsely  pitted  ;  the  upper  and 
lower  walls  very  variable,  in  the  low  rays  thick  and  coarsely  pUted,  in 
the  higher  rays  thin  and  barely  pitted  so  as  to  approach  cells  of  the 
second  order ;  the  lateral  walls  with  variou.sly  oval  or  lenticular  pits 
1-2,  rarely  6,  chiefly  2,  per  tracheid ;  (2)  cells  straight  or  variou.sly 
fusiform ;  the  terminal,  upper,  and  lower  walls  very  thin,  commonly 
much  broken  out ;  the  lateral  walls  with  broadly  oval  or  variously  len- 
ticular pits,  1-3  per  tracheid,  in  the  summer  wood  reduced  to  much- 
prolonged  shts.  Bordered  pits  in  1  row,  sometimes  in  pairs,  elliptical 
Pits  on  the  tangential  walls  of  the  summer  wood  wholly  wanting 

Tangential.  Fusiform  rays  somewhat  abundant,  medium,  rather  narrow,  the 
terminals  acute  or  somewhat  prolonged,  chiefly  composed  of  small  tra- 
cheids ;  the  cells  of  the  inflated  portion  chiefly  thin-walled  and  usi^ally 
much  broken  out,  but  dark  and  resinous.  Ordinarj-  rays  medium,  rather 
broad,  composed  of  thicker-  and  thinner-walled  cells  and  presenting  four 
principal  aspects:  (!)  low  rays  composed  of  thick-walled  parenchyma 
and  tracheids,  distinctly  fusiform;  (2)  i-seriate  rays  composed  of  sev- 
eral cells  of  thick-walled  parenchyma  and  tracheids,  usually  nonresinous ; 
(3)  i-seriate  rays  composed  of  terminal  tracheids,  t'  i'ck-walled  and 
thin-walled  parenchyma,  usually  much  broken  out  through  the  central 
region,  more  or  less  resinous ;  and  (4)  the  highest  rays  showing  inter- 
spersed, narrow  tracheids  with  strong,  local  contractions. 

A  tree  24-30  m.  high,  with  a  trunk  upwards  of  .90  in  diameter. 
Wood  light,  soft,  not  strong,  brittle,  close  grained,  and  compact. 

Specific  gravity o.... 

Percentage  of  ash  residue 030 

Approximate  relative  fuel  value 45/K. 

Coefficient  of  ela.sticity  in  kilograms  on  miliimeters  .     .     .  97a 

Ultimate  transverse  strength  in  kilograms 316. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  6680! 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  .     .     .  1687. 
(Sargent) 

Rare  and  local,  on  sandy  soil  in  proximity  to  the  seacoast,  California  (Sargent). 


I 


''i 


1.1 


I  i 


342 


ANATOMY  OF  THE  GYMNOSPERMS 


I 

;  1 


M.  P.  SaWntoiu,  Douglas 
Diggtr  Pint.     Bull  Pin* 

Transverse.  Growth  rings  thick,  variable,  often  double.  Summer  wood 
variable,  upwards  of  one  fourth  to  one  half  the  spring  wood,  from  which 
the  transition  is  somewhat  abrupt,  dense,  or  again  rather  open ;  the 
tracheids  very  unequal,  chiefly  in  irregular  rows,  the  larger  ones  often 
much  compressed.  Spring  tracheids  rather  large,  squarish-hexagonal, 
uniform  in  regular  rows,  the  walls  thickish.  Kesin  passages  medium, 
not  very  numerous,  chiefly  in  the  summer  wood  ;  the  epithelium  of  2  or 
more  rows  of  large,  irregularly  flattened  and  very  thin-walled,  somewhat 
resinous  cells,  often  forming  an  irregular  and  somewhat  extended  tract. 
Medullary  rays  prominent,  somewhat  resinous,  broad,  i  cell  wide,  dis- 
tant 2-10  rows  of  tracheids. 

Radial.  Rays  sparingly  resinous ;  the  tracheids  low  but  very  variable,  mar- 
ginal, predominant  and  sparingly  interspersed,  often  composing  the 
entire  structure  of  low  rays,  strongly  dentate  and  .somewhat  reticulate 
in  the  summer  wood.  Ray  cells  of  two  kinds :  ( i )  cells  rather  numerous, 
chiefly  in  low  rays ;  the  upper  and  lower  walls  thick,  strongly  but  irreR- 
ularly  pitted ;  the  lateral  walls  with  prominent,  round  and  bordered,  or 
simple  and  lenticular  pits,  2-5,  chiefly  4,  per  tracheid ;  (2)  cells  rather 
low  and  variable,  not  conspicuously  fusiform  ;  the  terminal,  upper,  and 
lower  walls  very  thin  and  entire ;  the  lateral  walls  with  variously  lentic- 
ular pits  without  an  obvious  border,  2-4,  chiefly  .:,  per  tracheid,  becoming 
reduced  to  1  in  the  summer  wood.  Bordered  pits  conspicuously  in  1-2 
rows,numerous,  elliptical,  becoming  smaller  and  round  toward  the  summer 
wood.    Pits  on  the  tangential  walls  of  the  summer  wood  wholly  wanting. 

Tangential.  Fusiform  rays  rather  numerous,  narrow ;  the  terminals  acute 
or  prolonged  linear,  chiefly  composed  of  tracheids ;  the  cells  of  the 
inflated  portion  large  and  very  thin-walled,  often  much  broken  out. 
Ordinary  rays  chiefly  low,  not  very  numerous,  ronresinous,  broad,  the 
tracheids  chiefly  terminal  and  much  narrower,  rarely  interspersed,  pre- 
senting four  principal  aspects:  (i)  thin-walled  parenchyma  with  termi- 
nal and  interspersed  tracheids ;  (2)  i-seriatc  rays  with  a  few  terminal, 
thick-walled  tracheids,  but  chiefly  composed  of  large  and  very  thin-walled 
parenchyma  cells ;  (3)  thin-walled  parenchyma  with  terminal  tracheids 
and  interspersed,  thick-walled  parenchyma ;  and  (4)  i -seriate  rays  com- 
posed of  tracheids  and  thick-walled  parenchyma. 

A  largr;  tree  24-30  m.  high,  with  a  trunk  upwards  of  1.20  m.  in  diameter. 
Wood  light,soft,not  strong, brittle  and  very  coarse  grained,compact,not  durable. 

Specific  gravity 0.4840 

Percentage  of  ash  residue 0.40 

Approximate  relative  fuel  value 48.18 

Coefficient  of  elasticity  in  kilograms  on  millimeters  ....  585. 

Ultimate  transverse  strength  in  kilograms 333. 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms     5387. 
Resistance  .  <  indentation  to  1.27  mm.  in  kilograms       .     .     2202. 
(Sar^, 
Ver)-  common  i-i  'he  foothills  region ;  Coast  Range  and  western  slope  of 
the  Sierra  Nevadas  below  4000  feet  elevation,  California  (Sargent). 


PINUS  343 

S9.  P.  tada,  Linn. 
/<«»A>//>  P,Ht.     Old  /•/./,/  I'ini 

^'"T,f!!^f?™T''M"*'  l?'"?**-  ^"""""'  ^-^  "P*"  "'  Hometimcs  rather 
dense,  often  double  and  often  equal  t..  the  sprinj;  wo.k1,  from  which  the 
Uansition  ,s  abrupt ;  the  tracheids  large,  stronglv  une.i^al  but  in  rather 
regular  rows.  Spring  tracheids  large,  s(,uari.sh,  the  walls  thin.  Kesin 
passages  numerous,  chiefly  in  the  .summer  wood,  very  large  ;  the  euithe- 
lium  composed  of  very  thin-walled,  sometimes  resinous  cells,  chiefly  in 
I  row  and  strongly  compressed  upon  the  face  of  the  tracheid  structure, 
more  rarely  becoming  2-rowed  in  part  and  forming  an  eccentric  tract 
of  limited  extent.  Medullary  rays  rather  prominent,  broad,  i  cell  wide, 
distant  2-8  rows  of  tracheids.  .  ,       .;    wiuc. 

Radial.  Rays  nonresinous ;  the  tracheids  sometimes  predominant  in  the  higher 
rays,  but  often  interspersed,  low  and  unequal  throughout,  .sparingly, 
rarely  strong;ly  reticulated.  Ray  cells  of  two  kinds:  (1)  ceils  rare  and 
occurrmgonly  (?)  in  the  low  rays,  where  they  are  conterminous  with  the 
tracheids ;  the  terminal  walls  thin  and  entire ;  the  upper  and  lower  walls 
thick  and  strongly  but  incompletely  pitted  ;  the  lateral  walls  with  round 
or  oval  pits,  upwards  of  6  per  tracheid;  (2)  cells  variously  fusiform, 
often  straight ;  the  terminal,  upper,  and  lower  walls  verj-  thin  and  com- 
inonly  much  broken  out ;  the  lateral  walls  with  variable,  oval,  or  lentic 
ular  pite,  1-6,  chiefly  2-4,  per  tracheid,  in  the  summer  wood  commonly 
reduced  to  i.  Bordered  pits  in  i  or  2  rows  or  often  1  row  or  pairs, 
elliptical.  Pits  on  the  tangential  walls  of  the  summer  wood  wholly 
wanting.  The  tracheids  of  the  summer  wood  sometimes  exhibit  a  dis- 
tinct  tendency  toward  the  formation  of  spirals. 

Tangential.  Fusifonn  rays  rather  high  and  narrow,  the  terminals  acute  or 
prolonged  and  finally  wholly  composed  of  .small  tracheids ;  the  cells  of 
the  inflated  portion  commonly  wanting.  Ordinarv-  rays  medium  and 
presenting  two  principal  a.spects:  (.)  higher  rays  composed  of  thin- 
walled  parenchyma  cells  chiefly  broken  out,  with  very  .small,  terminal, 
and  interspersed  tracheids,  the  latter  causing  local  contractions;  and 
(2)  lower  rays  of  thin-walled  parenchyma  much  broken  out,  rarely 
showing  a  thick-walled  parench>-ma  cell,  and  small,  terminal  tracheids. 

A  large  tree  24-46  m.  high,  with  a  trunk  upwards  of  1.50  m.  in  diameter. 
Wood  light,  not  strong,  brittle  and  very  coarse  grained,  not  durable. 

Specific  gravity 

Percentage  of  ash  residue o  26 

Approximate  relative  fuel  value     .........  i^.z-j 

Coefiicient  of  elasticity  in  kilograms  on  millimeters       '.     '.  11 28 

Ultimate  transverse  strength  in  kilograms 377I 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  6834. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  .  171Q 

(Sargent)  '  ^' 

Low,  wet  clay  or  sandy  soil ;  southern  Delaware  to  Tampa  Bay,  Florida, 
generally  near  the  coast ;  westward  through  the  Gulf  States  to  the  valley 
of  the  Colorado  River,  Texas,  and  northward  through  southern  Arkansas 
to  the  valley  of  the  Arkansas  River  (Sargent). 


.     \ 


[I'      '  I . 


:i,     1  ■ 


I 


344 


ANATOMY  OK  THK  (;YMN0SPERMS 


40.  P.  pdttttria,  Miller 
Leng-I^mtii  Pint.     Southtrn  Pint.     Ytlbw  P'h4 

Transverse.  Growth  rings  thin,  very  variable.  Summer  wood  dense,  often 
very  thin,  the  transition  from  the  spring  wood  very  abrupt ;  the  tracheids 
very  uniform  in  regular  rows.  Spring  tracheids  squarish,  rather  uniform, 
in  regular  rows,  often  radially  elongated,  the  wallr.  rather  thick.  Kesin 
passages  numerous  and  large,  chiefly  in  the  summer  wood ;  the  epithe- 
lium composed  of  large,  rounded,  often  resinous  cells  in  i  row,  fre- 
quently becoming  several-rowed  in  part  and  forming  more  or  less 
extensive  and  strongly  eccentric  tracts  about  the  canal.  Medullary  rays 
very  prominent,  broad,  i  cell  wide,  distant  2-10,  more  rarely  15,  rows 
of  tracheids. 

Kadial.  Kavs  sparingly  resinous  throughout :  the  ray  tracheids  often  inter- 
spersed, commonly  predomiiiant,  very  strongly  reticulated  throtghout. 
Kay  cells  of  two  kinds :  H)  rathi-r  few  but  prominent  and  conterminous 
with  tracheids  into  which  they  merge ;  the  terminal  walls  thin  and  not 
pitted ;  the  upper  and  lower  walls  somewhat  strongly  but  unequally 
thickened  and  pitted ;  the  lateral  walls  with  broadly  and  variously  len- 
ticular or  round  pits,  2-5  per  tracheid ;  and  (2)  very  long-fusiform  cells ; 
the  terminal,  upper,  and  lower  walls  very  thin  and  usually  much  broken 
out ;  the  lateral  walls  with  very  variable,  lentictilar,  or  oval,  sometimes 
ver)-  large,  pits,  2-6,  chiefly  about  4,  per  tracheid,  in  the  summer  wood 
reduced  to  I.  Bordered  pits  conspicuously  in  1-2  rows,  elliptical.  Pits 
on  the  tangential  walls  of  the  summer  wood  wholly  wanting. 

Tangential.  Fusiform  rays  not  numerous,  often  very  high,  acute,  the  linear 
terminals  much  prolonged  with  terminal  or  interspersed  tracheids,  but 
with  the  structure  very  commonly  wanting  except  at  the  extremities ; 
the  low,  inflated  portion  usually  showing  only  a  remnant  of  v  -ry  thin- 
walled,  delicate  tissue.  Ordinary  rays  medium,  rather  numerous,  broad, 
presenting  three  principal  aspects :  ( 1 )  low  rays  with  few,  thin-walled 
parenchyma  cells  much  broken  out,  and  terminal  tracheids  of  very  vari- 
able size  ;  (2)  higher  rays  of  several  large,  thin-walled  parench)rma  cells 
much  broken  out,  and  narrow,  oval  to  oblong,  terminal  tracheids,  rarely 
with  interspersed  thick-walled  parenchyma;  and  (3)  the  highest  ray.s 
composed  of  a  few  large,  thin-walled  parenchyma  cells,  with  small,  ter- 
minal, and  narrow,  often  high  and  interspersed  tracheids. 

A  tree  of  the  greatest  economic  value  18-29  "*■  l^'g^i  ^>th  a  trunk  upwards 
of  1.20  m.  in  diameter. 

Wood  heavy,  exceedingly  hard,  very  strong  and  tough,  coarse  grained,  com- 
pact, and  durable. 

Specific  gravity       0.6999 

Percentage  of  ash  residue 0.25 

Approximate  relative  fuel  value 69.82 

Coefficient  of  elasticity  in  kilograms  on  millimeters  .     .     .  1,488. 

Ultimate  transverse  strength  in  kilograms 490. 

Ultimate  resistance  to  longitudinal  cru.shing  in  kilograms  10,074. 

Resistance  to  indentation  to  1.27  mm.  in  kilograms  .     .     .  2,508. 
(Sargent ) 


PINU55  ,^- 

345 

bw,  wet  «,il.    Southeastern  Virginia  to  Tampa  Hay.  Florida-  nentla  < 
Kiver  inlexaM;  rarely  more  than  150  miles  from  the  coast  (Sargent). 

41.  P.  cabentU,  Griseb. 
S/atA  Pint.     Swamp  Pint 

^''""ZZ*.   ^.^"V'  "*"«!•  '■*"»''''•    *'^""""«'  ""^  variable,  deni«  or  ooen 
the  transition  from  the  spring  wood  usually  vtry  abruo      th^.r/.-K'TJ^' 

passages  numerous,  large,  chiefly  in  the  summer  wood  :  the  epithelium 
In  1-2,  rarely  3,  rows  of  rather  thin-walled.  usually  much  flattened^ 
resinous  eels.    Medullary  rays  prominent,  very  boad,,  cell  wWe" 

fiadial  Kzy*  sparingly  resinous ;  the  ray  tracheids  rather  hiuh  oredominan. 
ZIaVZ  'T «>:«^here  very  strongly  reticulated  Ra;'^dU  o  two 
kinds:  (i>  short-fusiform  ceils  equal  to  about  4  spring  tracheid,-  Z 
terminal  walls  thin  and  entire,  locally  thickened  or'^ily  pitted  ^  he 
tZ^'  *"'*^'-*"  T*'  '  "^'"  '""^  much  broken  down,  bu?  more'^^omrn'only 
thicker  and  irregularly  pitted,  these  two  forms  gradually  merginKS^fi 

Zlu!  T-I'^'^^  ?"P"';'^'''  •*"""^"'"«=''  conteLinous  wiTh  a^'nd  m^ 'fng 
ihi  fl  v!!**"  '  ""*=  ''"="'  *»"^  *"*>  ^"""We,  chiefly  lenticular pTtsT  6 
K-  '*^l!'  I"-*'  P^""  'i;""*"^''^' '"  •»'*  *"""""  w«"d  reduced  to  Ht  or 
becoming  obsolete.  Bordered  pits  in  1-2  rows,  numerous,  elliptical  in  the 
summer  wood  quickly  reduced  and  finally  obscure  rwhXwan^in/ 

icu^  o  rn  rn  °™  ;,»>''';'">'"  numerous,  high,  and  narrow,  the  temiinals 
acute  or  prolonged  and  composed  of  very  large,  broadly  oval  paren- 
Uorcoml's^d"'*  ?7.  '■■^^/r '"="  '^-ch'eidsf  the  short  inflated  ^^r- 
OrSinai^^^r  t   *'""-*='"'^'l   parenchyma  cells  much    broken   ^t. 

oval  rnm^ln  rj'""-"*'"'*'  ''™="^'  '"'='"""'•  »»^«  ""»  ^^^iefly  broadly 
oval,  composed  of  dominant  parenchyma  cells  with  chiefly  terminal 
sparingly  interspersed,  often  high,  and  narrow  tracheids.  ' 

A  tree  24-30  m.  high,  with  a  trunk  upwards  of  .90  m.  in  diameter 

^  durabl'e"'"'''"^'^  '"'"''  ^''^'  ''™"^'  '''"^'''  '"^''^  «''''"''*•  '^'""P**^'- 

Specific  gravity       .     .     . 

Percentage  of  ash  residue     '.     \ °olf°'^ 

Approximate  relative  fuel  value  ,°b 

Coefficient  of  elasticity  in  kilograms  on  millimeters  '.     '  '.    ^  577    ^ 
Ultimate  transverse  strength  in  kilograms    ...  5^0' 

Ultimate  resistance  to  longitudinal  crushing  in  kilograms  '  10,626' 
Kesistance  to  indentation  to  1.27  mm.  in  kilograms  .  2  985 


.  1 

I-l 


•,^ 


St  I 


346 


ANATOMY  OF  THE  CAMNOSHERMS 


South  Carolina  and  xnuthward  near  the  coaitt  tu  the  Kloriiia  Key*  wculward 
along  the  (iulf  toasit  to  the  I'carl  River,  L<>ul»iana,  not  nunc  than  o  or  (m 
mileii  inland;  alio  in  the  Wcitt  Indie*  (Sargent) ;  Uahanuw  and  IhIc  of 
Pine*  (Shaw). 

B.  HITYOXYLON  (Finoxylon) 

/■iuti/  Sptdn  Only 

49.  P.  dMOtOlM,  Knowlton 

"  Tranrvtrst.  Annual  rings  broad  and  very  distinct,  even  to  the  oaked 
eye,  being  2-45  ram.  in  width.  Distinction  l>etween  the  xpring  and 
autumn  wood  very  plain,  the  former  appearing  as  broad,  white  bands, 
and  the  latter  as  denae  black  bandit  of  varying  width.  Under  the  mit  nj. 
kcope  the  line  of  demarcation  between  fall  and  spring  wood  Ik  obser\ed 
to  be  very  sharp  indeed.  The  fall  wtiod  consist.^  of  thick-walled  cells 
of  an  elliptical  or  oblong  outline,  rather  loosely  placed.  The  aucceeding 
spring  wood  i»  compoHcd  of  very  large  cells  with  relati'  ely  thin  walK. 
The  medullary  rays  are  long  and  quite  thick-walled.  There  are  no  resin 
cells  in  the  wood.  The  re^-in  pa.ssage8  are  present  and  (juite  numerous. 
They  do  not  seem  to  be  cunfined  to  any  particular  portion  of  the  ring, 
but  are  scattered,  being  perhaps  m<)»t  numerous  in  the  fall  wood.  They 
are  of  relatively  large  size  and  lined  with  thin-walled  epithelium. 

"  Radial.  The  walls  of  the  spring  and  summer  wood  have  2  rather  irreg- 
ular rows  of  large,  bordered  pits.  In  rare  ca.ses  these  pits  are  in  a  single 
row.  The  average  size  of  tlie  outer  cirtk  is  .025  mm.,  that  of  the  inner 
circle  about  .015  mm.  The  crlls  ot  the  ays  are  rather  long,  covering 
the  width  usually  of  some  4  or  more  ceils  of  the  spring  wootl.  They 
are  rather  thick-walled,  the  walls  l)eing  .strongly  dentate  or  somewhat 
irregularly  thickened.  The  ray  cells  are  provided  with  ui  few  scattered, 
bordered  pits,  usually  only  I  to  the  width  of  a  spring  cell  of  the  wood, 
although  not  rarely  there  are  2  in  a  similar  idth.  They  are  always  in  1 
row  on  the  ray  cell. 

"  Tangential.  Medullary  rays  in  a  single,  uperimposed  series,  from  1  to 
rarely  30  cells,  the  average  being  from  5  12  cells  high.  None  of  the 
rays  in  the  sections  examined  are  of  the  fusiform  type  or  contain  resin 
pas.sages.  The  wood  cells  are,  as  far  as  can  be  made  out,  without  pits 
or  markings  of  any  kind"  (Knowlton). 

Trunks  of  medium  size ;  material  silicified. 

Upper  (?)  Jurassic  near  Sturgis,  South  Dakota  (Knowlton). 


43.  P.  Alderaonl,  Knowlton 

"  Transverse.  The  annual  rings  are  very  distinct,  being  plainly  discemilile 
to  the  naked  eye.  Some  of  the  broadest  rings  are  fully  9  mm.  wide  and 
none  less  than  6  mm.  The  demarcation  between  fall  and  spring  wooa 
is  very  pronounced,  the  cells  of  the  fall  wood  being  small,  conipressrd, 
and  thick-walled,  while  those  of  the  early  spng  w^iod  are  very  lart;e, 
and,  of  course,  thin-walled.  The  cells  of  the  yi-ri.ig  and  summer  w.mhI 
continue  for  a  width  of  5  mm.,  but  little,  if    .iiy,     .minished  in  si/i-. 


In  I  YOXVI.ON 


347 


I  rien  ^\w^  hecom*  HlJi-htl v  MnalWr  awl  lit.      r-walled  and  imm  gradually 
Bto    n,  fall  «,H  .1     ihe  n^i„  ,1,h,«  ,,re  vt  ,  larxc.    They  arc  not  found 
in  Ih.     umnuf  wojxl,  I.,..  ,h;i  ur  irre^iiiarly  In  the  early  fall  an.d  late  tall 
wooci      The  n.rdullar>  r.iVH  as  ohwrvcd  in  thi*  w,  M„n  arc  stiaji{hi  .,nd 
Hcpara.ad  In  j  «  or  lo  ro».  of  woo<l  cells.    The  individval  cdU  are 
apparently  long, 
"AWw/.  Notwith»tanUinK  il)e  fact  that  the  wood  wems  to  be  perfectly  pre- 
sc'vwl.  It  does  nut  re%eal  the  structure  well  in  this  «:ction      The  wood 
ceUs  are  Men  to  h.-  Hharp-pwnted  where  they  join.    They  are,  of  tourne. 
broad  in  the  spring  and  summer  wood  and  very  narrow  in  tf.e  fall  wood 
It  IS  very  difficult  'n  make  out  the  pit.s  but  in  exceptionally  well-pre- 
served portion*  a  few  may  lie  faintly  seen.    They  are  scattered,  but  in 
a  Hingle  strten.    They  are  so  obscure  that  no  satisfactory  measurements 
can  be  tiiade.    The  medullary  rays  in  this  section  are  long,  thick-walled 
and  without  markings,  so  far  as  can  be  it,  »de  out 
"  raMi^tnltal.  Tl^,*  section  is  verj-  p|,.in.    The  medullary  rays  ar-    lun.wrous 
and  in  ,,  single  series,  although  occasionally  a  ray  roav  be  ob«erv fd  in 
which  tht  c  are  2  senes  ..i  tells  for  a  short  distai  icl    In  suih  cases 
tfie  tells  ire  alwavs  smaller  than  the  ordinary  ray  tells.    The  number 
(if  cells  making  up  each  ray  ranges  from  2  to  30  or  more,  but  the  average 
number  is  al.out  ^-15.    The  rays  in  which  there  is  a  re.sin  duct  are 
t  ither  rare      I  he  duct  is  large,  taking  up  all  the  width  of  the  ray.    Thf 
remainder  ,„     ,e  ray  \s  3  rows  of  cells  high  in  the  middle,  and  is  reduced 
i:^»  I  at  Uie  ..xtrcm.ties.    The  wood  i    Is  show  plainly  in  this  section 
I  hpv  are  not  provided  with  pits  or  other  markings"  (Knowlton). 

Inmks  ()!  lar-e  size,  3-5  feet  in  diameter.    Material  silitified. 
I  vri,ar>  of  the  Ydlowsionc  National  I'ark,  at  Specimen  Kidgc,  near  head 
-A  Crvtal  Creek,  anr'  Yancy  Fossil  Forest  (Knowlton). 


44.  P.  unethystinttin,  Kno-vkon 

"  Tramrcrse.  Much  like  V.  Aldersoni  except  that  the  rings  are  narrower, 
xhv  cells  of  the  spring  and  summer  woikI  are  smaller,  and  the  late  fall 
cells  have  thinner  walls.  The  resin  du<  ts  a-o  ■;  much  the  same,  being 
in  general  only  a  little  smaller     A  fi:  ..••  ,  i,,  the  summer  wood, 

but  most  of  them  are  in  the  f.ill  v^  he     »   ;  are  not  nearly  so 

numerous  as  in  the  last  species.  Tre>  art  often  separated  by  as  many 
a.s  25  rows  of  wood  cells. 

"  Kat/ial.  The  radial  section  of  nearly  .ill  woods  from  the  Yellowstone 
National  Park  is  more  or  less  obscure.  The  one  under  consideration 
is  no  exception  to  this  rule,  and  it  is  only  alter  considerable  search  that 
the  pite  can  be  determined  They  are  in  a  single  row  and  are  rather 
small.  They  are  so  obscure  that  it  is  impossible  to  make  trustworthy 
measurements.  The  medullar)-  rays,  as  seen  in  this  section,  are  com- 
posed of  long,  thin-walled  ct  lis,  and,  so  far  as  can  l>e  determined,  they 
are  without  pits  or  other  markings. 

"  Tangential.  This  .section  shows  the  structure  very  plainly.  The  medullary 
rays  are  abundant  and  always  in  a  single  .series,  except  the  large,  com- 
pound ones.  The  numlier  of  cells  in  each  ray  varies  from  2  to  10  or  1 2, 
the  average  number  being  about  6.    The  compound  ravs  inclosing  the 


348 


ANATOMY  OF  THE  GYMNOSPERMS 


I; 


resin  ducts  arc  rather  small,  with  3  rows  of  cells  in  the  middle  portion. 
No  markings  can  lie  made  nut  nn  the  wood  cells  in  this  section " 
(Knowlton). 

This  species  is  very  closely  allied  to  the  preceding,  and  should  perhaps  be 
referred  to  it.  The  main  j)oints  of  difference  are  the  following:  smaller 
resin  ducts  that  are  occasionally  found  in  the  summer  wood ;  smaller 
wood  cells  throughout ;  smaller  and  shorter  compound  medullary  rays ; 
ordinary  rays  always  in  a  single  series  of  2-12  cells  (average  6)  instead 
of  2-30  or  more  (average  12)  (Knowlton). 

This  species  cannot  be  separated  from  the  preceding  on  the  basis  of  the 
characters  given,  and  it  is  undoubtedly  the  same,  though  recognized  here 
provisionally  (I). P. P.). 

Trunks  of  small  and  medium  size.    Material  siliciiied. 

Tertiary  of  the  Yellowstone  National  Park  at  Specimen  Ridge,  near  the  head 
of  Crj'stal  Creek  (Knowlton). 

45.  P.  Columbiana,  Penh. 

Transverse.  Growth  rings  variable  though  generally  very  broad  in  large 
stems.  Spring  wood  usually  predominant,  the  transition  to  the  summer 
wood  gradual  but  in  the  narrower  rings  more  or  less  abrupt  and  some- 
times conspicuously  so ;  the  tracheids  large,  thick-walled  and  often  con- 
spicuously so,  definitely  rounded,  often  radially  oval,  chiefly  uniform, 
more  or  less  eoual,  in  regular  radial  rows.  Summer  wood  conspicuous, 
dense,  and  ofteii  rather  thin.  The  structure  as  a  whole  is  that  of  a  rather 
dense  wood  of  medium  hardne.ss.  Medullary  rays  prominent,  not  very 
numerous,  resinous,  and  distant  upwards  of  9  or  more  rarely  1 5  rows  of 
tracheids.  Resin  pa.ssages  conspicuous,  rather  large,  and  scatterin}; 
throughout  the  growth  ring,  the  parenchyma  cells  large,  thin-walled, 
and  in  2  rows,  or  forming  large  and  irregular  tracts  upwards  of  6-9 
tracheids  wide,  resinous ;  thyloses  not  obvious. 

Radial.  Medullary  rays  resinous ;  the  tracheids  rather  numerous,  marginal 
and  intersijersed,  not  obviou.sly  predominant,  very  variable  and  often 
as  high  as  or  higher  than,  long,  sparingly  dentate  ;  the  parenchyma  cells 
all  of  one  kind  and  rather  thin-walled,  straight,  and  equal  to  about  4 
wood  tracheids;  the  upper  and  lower  wails  strongly  (?)  pitted;  the  terminal 
walls  straight  or  diagonal  and  apparently  not  pitted;  the  lateral  walls 
with  simple,  round  or  lenticular  pits  of  medium  size,  2-4,  chiefly  2,  per 
tracheid.  Bordered  pits  on  the  tangential  walls  of  the  summer  tracheids 
small  and  not  numerous ;  those  of  the  radial  walls  rather  large,  round, 
or  oval  in  I  compact  row,  and  generally  numerous. 

Tangential.  Fusiform  rays  rather  numerous,  short,  the  broad  central  tract 
with  thin-walled  parenchyma  chiefly  broken  out,  the  unequal  terminals 
composed  of  broad,  oval  cells  chiefly  in  1  row.  Ordinary  rays  low  i.> 
medium,  i-seriate,  not  materially  contracted  by  the  interspersed  tra- 
cheids; the  parenchyma  cells  somewhat  unequal  and  variable  fnmi 
oblong  to  oval  or  broad  and  round. 

Calcified  fragments  of  stems  and  branches,  and  also  cones  in  the  Tertiary 
of  Kettle  River,  near  Midway,  British  Columbia. 


1'irvoxvi.oN 

46.  p.  Petli,  Knowlton 


349 


^Z".-    .J"  I^^T  "''*'*''  "^"^  '»'«  ^^'  »"d  Mrly  sprinK  wood     The 
contrast  m  he  thickness  of  the  cells  makes  a  very  clearKS  rin/ 

yCTf  n^  ^°*"'  T'*  ""7  broad,  being  in  some  cases  Mly  ,o  mm" 
">pJi/  7/'""»'-y.">«  ^''"'^  in  this  section  also  as  long,  slen,  "  ce  Is 
-RaAal.  Ihe  specimens  are  in  a  fine  state  of  preserva  ion     The  cells  of 
the  spnng  and  summer  wood  are  very  broad  and  ma  ked  «ith%  siLli 
*enes  of  large,  scattered,  bordered  pi'ts.    The  meduHa^  ray    are  prom 

"  Tangential.  The  medullary  rays  are  arranged  in  a  single  series  of  from  - 
themidTnf  '  2o  superim,x>sed  cells.*  The  resin^tubeToccurrir  i„" 
the  midst  of  a  medullary  ray  are  quite  numerous.    There  are  no  recoJ^ 

jKnowitCLr"" "'" " ""  ''"^•="'"'  "^"'^  ofThr;;^"S' 

Material  silicified. 

Miocene  of  the  upper  Gallatin  Basin,  Montana  (Knowlton). 

47.  P.  chasense,  Penh. 

7V««.«/^r.r<f  Tracheids  chiefly  in  regular  radial  rows,  very  variable  in  si/e 
•squarish,  about  44x44/.  broad;  the  w.-ills  .2.5  u  S  Me LhTv* 
rays  numerous,  chiefly  .  cell  wide,  occasionallv  2-3  .  eriate  C  r  "w  h 
rings  wholly  wanting.     Resin  cells  and  resin  canals  not  represented 

Aad.al.  Ray  cells  all  of  one  kind;  straight,  equal  to  2-4  traS,  the 
nC^;  "I''  ^^r  ^■""■''  "^'^  ""^  "«'  P'«"'  =  «he  terminal  walls  Sin  toX 
minnhlh'^'jK '''•"'''"'*'  '^^  ''*'""'^'"^*-'  °^  '^e  lateral  walls  not  deter 
minable,  but  the  pits  an;  probably  round.  Bordered  pits  in  1  /rows 
ch^^fl^y  2  rows,  round  or  hexagonal,  .2.5,.  broad,  .he'oritlce  probably 

^"Xrlif  f^^^  ''^  •^■''  >'"'*''=  (')  '••''^^''««'=  ray.s,  the  cells  oblong    2,  « 
broad  often  2-ser.ate  in  part ;  and  (2)  fusiform  ray.s,  the  terminals  li^ei^ 
and  of  the  structure  of  the  .-.seriate  rays;  the  centra!  '  Vctv'er    broad 
nearly  round  ,  the  cells  large,  thin-walled,  irregular.  anS  inc?osS   a 
small,  central  resin  passage  with  large  epithelium  cells.  ^ 

Material  silicified.    Specimens  represented  by  small  fragments  of  stem 

Klsas^frosrerr™^'"^"  (^^™'^">  "'  ^'"°"  ^^-•'>  ^^^^   bounty. 


\*. 


48. 


P.  8Utenene«,  Jeff,  and  Chrys. 


rransi>erse.  Growth  rings  vari.ible,  chiefly  narrow  but  usually  well  defined  • 
summer  wood  very  vari.-il.Ie.  of  ,h/  narrower  rings  .  -  s!  1  uf  of  The" 
^v!.    .'■,.""*^'.'"u."y  '"'^heids  thick  and  constituting  upwards  of  two 

Ib'rtt  the"'tS''"'="'  'T""°"  ^'°"'  thesprin,^wLi  ^mewhat 
abrupt,  the  broader  growth  rings  sometimes  showing  2  zones  of 
summer    wood.     Trachcids    round-hexagonal    or    rectangular     rather 


M 


350 


ANATOMY  OF  THE  GYMNOSPERMS 


uniform  but  conspicuously  unequal,  disposed  in  unequal  and  some- 
what irregular  rows;  those  of  the  spring  wood  thin-walled,  about 
32  X  39  ^  those  of  the  summer  wood  rather  thin-walled,  about  19  x  29/i. 
Medullary  rays  very  resinous,  broad,  1  cell  wide,  and  distant  about  2-8 
rows  of  tracheids.  Specialized  resin  cells  wholly  wanting.  Resin 
passages  numerous,  large,  chiefly  in  the  spring  wood  and  filled  with 
prominent,  resinous  thyloses,  the  epithelium  1-2  cells  thick,  and  not 
extended  into  parenchymatous  tracts. 

Radial.  Bordered  pits  very  numerous  in  1  row,  rarely  contiguous ;  round, 
more  rarely  oval,  and  about  I7S  M>  the  round  orifice  about  7  /*;  in 
the  summer  wood  somewhat  reduced.  Pits  on  the  tangential  walls  of 
the  summer  wood  prominent,  large,  somewhat  numerous.  Medullary 
rays  very  resinous ;  ray  tracheids  wholly  wantk:ig ;  parenchyma  cells 
all  of  one  kind,  more  or  less  contracted  at  the  ends,  very  /ariable 
but  generally  equal  to  about  3-5  spring  tracheids ;  the  upper  and 
tower  walls  strongly  and  rather  frequently  pitted  ;  the  terminal  walls 
coarsely  pitted  or  locally  thickened ;  the  lateral  walls  with  rather  small, 
oval  pits,  chiefly  1  per  tracheid  throughout,  or  in  the  marginal  cells 
and  low  rays  2  per  tracheid. 

Tangential.  Fusiform  rays  numerous,  medium  ;  the  cells  thick-walled  ;  the 
frentral  tract  broad  and  occupied  by  i  large  resin  canal  filled  with 
thyloses;  the  terminals  chiefly  short  or  rarely  prolonged  with  1-2 
seriate  cells.  Ordinary  rays  very  variable  but  chiefly  low  to  medium, 
sometimes  more  or  less  2-ser'ate  in  part ;  very  numerous ;  the  cells 
broad  but  variable  and  round,  oval  or  squarish,  chiefly  equal ;  in  the 
low  rays  commonly  becoming  oblong. 


The  middle  Cretaceous  at  Kreischerville,  Staten  Island, 
form  of  lignite  (Jeffrey). 


Material  in  the 


49.   •  •  P.  adtuatense,  Jeff,  and  Chrys. 

Transverse.  Growth  rings  rather  broad  but  thin,  the  limits  obscured  by 
displacement  of  structure  ;  summer  wood  chiefly  broad,  the  transition 
from  the  spring  wood  apparently  gradual.  Tracheids  all  rather  thin- 
walled,  those  of  the  spring  wood  about  26.7  x  44.5  ^.  Medullary  rays 
numerous,  prominent,  resinous,  broad,  1  cell  wide  and  distant  about 
2-5  rows  of  tracheids.  Kesin  canals  rather  numerous,  chiefly  in  the 
summer  wood  and  central  to  broad  tracts  of  parenchyma ;  devoid  of 
thyloses,  rather  small,  regularly  oval  or  round,  the  epithelium  composed 
of  a  single  layer  of  rather  small,  rounded,  and  somewhat  thick-wallcd 
cells.  Wood  parenchyma  resinous,  the  cells  large,  thin-walled  ;  forminj,' 
extensive  and  prominent  tracts  about  the  resin  canals  often  427  x  570  /i 
broad. 

Radial.  Bordered  pits  in  1  row,  somewhat  distant  and  not  numerous ; 
round,  about  24.6  ^  broad,  the  lenticular  orifice  showing  a  cross  ;  ndt 
much  reduced  in  the  summer  wood.  Pits  on  the  tangential  walls  of 
the  summer  tracheids  not  determinable,  apparently  wanting.  Medul 
lary  rays  resinous  ;  ray  tracheids  apparently  wanting  ;  the  parenchym.i 
cells  all  of  one  kind,  not  contracted  at  the  ends,  equal  to  about  5-  ri 
wood  tracheids ;  the  upper  and  lower  walls  rather  thick,  distantly  and 


PITYOXYLEN 


351 


coarsely  pitted  ;  the  tenninal  walls  rather  thin  and  locally  thickened  ■ 
the  lateral  walls  with  round,  bordered  pits  about  1 1.5  /i  broad,  chiefly 
I,  or  sometimes  2,  per  tracheid,  the  orifice  lenticular,  diagonal.  Wood 
parenchyma  resinous ;  the  cells  cylindrical,  2-several  times  longer 
than  broad,  the  radial  walls  with  rather  small  pits. 
Tangential.  Ordinary  rays  resinous,  numerous,  variable,  low  to  high,  1-2 
senate,  or  sometimes  3-seriate,  and  approximating  to  the  fusiform 
type  through  various  gradations,  but  always  devoid  of  resin  canals  • 
the  usually  large  cells  very  unequal  and  very  variable,  ranging  from 
oblong  to  oval,  round  or  transversely  oval,  the  strong  inequality  and 
variability  giving  a  marked  irregularity  of  form  to  the  ray  as  a  whole. 
Fusiform  lays  rather  numerous,  low  to  high,  the  central  tract  occupied 
by  I  rather  small  resin  canal  devoid  of  thyloses,  but  with  small  and 
thick-walled  epithelium  cells ;  the  terminals  short  or  sometimes  un- 
equally prolonged  to  considerable  length.  Wood  parenchyma  resinous, 
the  short-cylindrical  cells  with  thin  walls  and  bearing  pits  on  all  their 
walls.  Rudimentary  spirals  may  be  seen  in  the  tertiary  layer  of  many 
of  the  tracheid  walls.  ■' 


Cretaceous  (?)  of  Third  Cliff,  Scituate,  Massachusetts, 
form  of  lignite  (Bowman). 


Material  in  the 


B    r 


lit 

11 
11 


I       ■%, 


If  'W^' 


APPENDIX  A 

DATA    FOR   TABLE   OF   ANATOMICAL  CHARACTERS.  IN 
IDENTICAL  SERIES 


I. 
2. 
3- 
4- 
S- 
6. 

7. 


Spiral  tracheids. 

Bordered  pits  in  1-3  rows. 

Bordered  pits  in  1-2  rows. 

Bordered  pits  in  i  row. 

Pits  on  the  tangential  walls  of  the  summer  wood. 

lateral  walls  of  the  ray  cells  with  bordered  pits. 

I -seriate  rays. 

8.  Terminal  walls  of  the  ray  cells  thin  and  entire. 

9.  Resin  cells. 

10.  Terminal  walls  of  the  ray  cells  locally  thickened. 

1 1.  Terminal  walls  of  the  ray  cells  strongly  pitted. 

12.  Ray  tracheids. 

13.  Resin  passages. 

14.  Fusiform  rays. 

15.  Thy  loses  in  the  resin  passages. 

16.  I.ateral  walls  of  the  ray  cells  with  simple  pits. 

17.  Ray  cells  of  two  kinds. 


Resin  cells  scattering. 

R';sin  cells  zonate. 

Resin  cells  grouped. 

Resin  cells  on  the  outer  face  of  the  summer  wood. 

Ray  tracheids  marginal. 

Ray  tracheids  interspersed. 

Ray  tracheids  dentate. 


A.  Number  of  species. 

B.  Percentage  value  of  genus. 


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LITERATURE 

Anderson,  A.  P.   (1)  Ueber  abnorme  Bildung  von  Harzbehaltem.     MUnchen, 

1896. 
(>)  Comparative  Anatomy  of  the  Normal  and  Diseased  Organs  of  Abies 

balsamea  affected  with  vEcidium  elatinum.     Bot.  Gaz.,  XXIV,  30^3441 

1897  (Plates  XIV- XV). 
BoULGER,  G.  S.    (79)  Wood:  a  Manual  of  the  Natural  History  and  Industrial 

Applications  of  the  Timbers  of  Commerce.    London,  1902. 
BovEY,  H.  T.    (8)  Theory  of  Structures  and  Strength  of  Materials,  pp.  213, 

215. 

(4)  Presidential  Address.    Trans.  R.  S.  (Canada),  II,  iii,  3-24,  1896. 

(6)  Results  of  Experiments  on  ths  Strength  of  White  Pine,  Red  Pine, 

Hemlock,  and  Spruce.    Trans.  Can.  Soc.  C.  E.,  XII,  207,  1S97. 
(6)  Results  of  Tests  of  White  Pine  of  Large  Scantlings.    Trans.  Can.  Soc. 

C.  E.,  VII,  13s,  1893. 
(7)  The  Strength  of  Canadian  Douglas  Fir,  Red  Pine,  White  Pine,  and 

Spruce.    Trans.  Can.  Soc.  C.  E.,  IX,  69,  1895. 
Brixton,  N.  L.,  and  Brown,  A.    (•)  Illustrated  Flora  of  the  Northern  United 

States  and  Canada.     New  York,  1896. 
Campbell,  D.  H.   (9)  Text-Book  of  Botany,  p.  335. 
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Forestry  Div.,  Bull.  '    -887. 
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153-168,  1898. 
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1887. 
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their  Decay  in  the  Roadbed.    U.  S.  Dept.  of  Agriculture,  Forestry  Div., 

Bull.  I,  1887. 
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Engler,  a.    (16)  Naturlichen  Pflanzenfamilien,  II,  24  tt  seq. 
Engler,  a.,  and  Prantl,  K.   (17)  Naturlichen  Pflanzenfamilien,  II,  7-127. 
Essner,  B.    (18)  Diagnosticher  Werth  der  Anzahl  und  Hohe  der  Markstrahlen 

bei  den  Coniferen.    Bot.  Centralbl.,  XII,  407,  1882. 
Fischer,  H.    (19)  Ein  Beitrag  zur  vergleichenden  Anatomie  des  Markstrahl- 

gewebes  und  der  Jahrkichen  Zuwachszonen  im  Hblzkorper  von  Stamm, 

V       ;1  und  Aesten  bei  Pinus  abies,  L.    Flora,  LXVIII,  1885. 

362 


hit^Miriaft- 


LITERATURE 


363 


^:|)  .  of  Agriculture,  Forestry 


K:ad.  IIf.nrv.   (90)  Wood  Pre-ervatior,.    U.  S.  1, 

L>IV.,  Hull.    I,  pp.  yj-^S,    ,887. 

GiiPPF-RT.  n.  R.   (M)  Kossilen  Coniferen.    Leiden,  ,850 

ARTIG,r.EoKoI.,„w,r..    (81)   I.el,rbuch  fur  ForMc.    S.ut.gart,  1877 
hT^::  TnlTinT^'':  ""  '";:!!''"  N^'de.wa.dbaume.  ^e^L  ^^885. 
HolucVa    J^^^  der  Ho.zp«a„.en.   Berlin'.  .878. 

,  *im  jtKhREY,  li.  c.  (17)  Affinities  of  Certain  Cretaceous  Plant 
Remains  commonly  referred  to  the  Genera  Dammara  and  Brachyrhyllum 
Amer.  Nat..  XL,  No.  471,  pp.  189-2.5.  .906  (Plates  I-V). 

"'"^.liles''pa?t*l   Th"  ^""'T'"  """"""^  ""'•  ''''y'°8''"y  °^  'he  Conif. 

—  (»»T  A  Fo«  I  ^  r'  ''\^"°'*-    ^""-  "°'"°"  «°-  ^'="-  «''*'•.  ■903. 

2,-     f  1  '*'*'^  '*''^''''''-     ^°'-  ^''^-  XXXVHI, 

JEKFREVEC   andCHRvsLKK.M.A.   (M)  On  Cretaceous  Pityoxyla.    Bot.  Gaz 
XLH,  No.  I.  pp.  ,-14,  ,906  (Plates  I-II).  ' 

Knowlton  F  H.  (S6)  New  Species  of  Fossil  Wood  (Araucarioxylon  arizonicum) 
from  Arizona  and  New  Mexico.    Proc.  U.  S.  Nat.  Mus.,  XI.  ,888  ^ 

—  (27)  Descnption  of  Two  New  Species  of  Fossil  Coniferous  Woods  from 
««.    .  'v    ^°"'^"*-    ^"^-  "•  ^-  ^="-  ^'"*-  >^I.  S-8.  .888. 

~     Descrim"r^°p''',*'«™"  ^■■-"rioxylon  of  Kraus,  with  Compiled 
De  captions  and  Partial  Synonomy  of  the  Species.    Proc.  U.  S.  Nat.  Mus 

Ail.  601-617,  1890. 

~  ''xiiLX:8V.8r """ ''"'"  '"'^'  '"'''"'•  "'""•  "■  '•  ^^»-  ^-■• 

~^'sir:.tl..T6:l^^^^  ''«"^"'  °^  "-^   ''°'°--  ^°""---    -■  -  Oeol. 

—  (81)  Descripaon  of  a  Supposed  New  Species  of  Fossil  Wood  from  Montana 

BuU.  Torr.  Bot.  Club,  XXIII,  250-251,  1896. 

—  (88)  Description  of  Fossil  Wood  and  Lignites  from  Arkansas.    Ann.  Kept 

Geol.  Surv.  of  Arkansas,  II,  249-266,  1889  ^ 

(88)  Description  of  Known  Fossil  Plants  from  the  Laramie  of  the  Yellow- 

st^one  National  Park.    U.  S.  Geol.  Surv.,  Monogr.  XXXII,  Part  II,  eli-Z, 

~~  ^  U^  SC^Tr"  °i"!r  ^'■^'='"°"^  ^"'l  Tertiary  Plants  of  North  America, 
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Macoun,^Johx.   (88)  Catalogue  of  Canadian  Plants.  Exogens.  Geol.  Surv.  Can.. 
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SSX,  xx''!'.."-"  °"  "■•  "'"■'  -  '■—  •"-'  --'«-- 

if!!  V"^  Cypresses  of  Monterey.    Garden  and  Forest,  VII.  298 
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Murray,  A.   (48)  Edinburgh  New  Phil.  Jn'I,  .n.  s.,  I. 


ill 


364 


ANATOMY  OF  THE  GYMNOSPERMS 


I- 

6 


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51-79,  1900. 

(46)  Notes  on  Tertiary  Plants.    Trans.  R.  S.  (Canada),  IX,  iv,  33-95,  1903- 

(47)  Contributions   to   the   Pleistocene   Flora  of  Canada.    Trans.  R.  S. 

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Bristol,  i8<)8;  pp.  7-12,  Bradford,  1900. 
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1890. 
(80)  Notes  on  the  Cretaceous  and  Tertiary  Plants  of  Canada.    Trans.  R.  S. 

(Canada),  VIII,  iv,  31-91,  1902. 
(81)  Notes  on  Tertiary  Plants  from  Canada  and  the  United  States.    Trans. 

R.  S.  (Canada),  X,  iv,  57-76,  1904. 
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(88)  The  Relation  of  Annual  Rings  to  Age.    Can.  Rec.  Sc,  I,  162. 

(84)  Some  Peculiarities  of  Plant  Growth.    Science,  III,  354. 

(88)  An  Ancient  Blaze.    Can.  Rec.  Sc,  III,  500. 

(86)  Osmundites  skidegaiensis.    Trans.  R.  S.  (Canada),  VIII,  iv,  3-29,  1902. 

(87)  Notes  on  Nematophyton  crassur.i.    Proc.  U.  S.  Nat.  Mus.,  XVI,  1893. 

(88)  Notes  on  Devonian  Plants.    Trans.  R.  S.  (Canada),  VII,  iv,  19-30, 1901. 

(89)  The   Anatomy  of    the    North    American    Coniferales.     Amer.   Nat., 

XXXVIII,  243-273;  33'-3S9;  523-534;  691-723,1904. 
(80)  Variation  of  Water  in  Trees  and  Shrubs.    Amer.  Nat.,  April,  1886; 

Can.  Rec.  Sc,  II,  105. 

(88)  A  Blazing  Beach.    Science,  XXII,  794-796,  1905. 

Pierce,  J.  G.    (60)  Studies  on  the  Coast  Redwood.    Cal.  Acad.  Sc,  II,  83-106, 

1901. 
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Prantl,  K.   (69)  Naturiichen  Pflanzenfamilien,  II,  33-40. 
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of  Agriculture,  Forostry  Div.,  Bull.  13,  pp.  I33-M3- 
Russow,  E.   (64)  Zur  Kenntniss  des  Holzes,  Insonderheit  des  Con.ferenholzes. 

Bot.  Centralbl.,  XIII,  29-40;  60-68;  95-109;  134-144;  itJ-173,  1883. 
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United  States,  IX  (the  whole  volume),  1880. 

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ScHROEDER,  J.   (67*  Iltilz  der  Coniferen.    Dresden,  1872. 

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LITERATURE 


365 


Scorr   D.  H.   (70)  The  Anatomical  Charac.en,  presented  !,;■  ,he  Peduncle  of 

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20th  Ann.  Kept.  U.  S.  Geol.  Surv..  Part  11,  4.8-4..,  .898-.i-99. 

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Weiss,  G.  A.    (76)  Anatomie  der  Ptianzen.    VVien,  1878 

WtLUAMsoN,  W^C.   (76)  On  the  Structure  and  A^nities  of  Some  Stems  from 

the  Coal  Measures.    M.  Mic.  J.;i,  II,  66-72. 
V,  ITTSTEIN  G  C.    (77)  Organic  Constituents  of  Plants.    Translated  by  Baron  F. 

von  Mueller,  Melbourne,  Australia,  1878 
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I 

I     t 


INDEX 


Abies,  10.  14.  SI,  58,  76,  82,  83.  88,  80, 
94.  '04.  107.  iia-128,  138-1SJ,  156, 
•57. 187.  "96.  «97.  »SJ  i  amabilu,  1  ij, 
115,  l»i,  255,  j6o,  359;  balsamea,  88, 
102,  112,  118,  140,  141,  .54,258.359; 
bracteata,  102, 121,  138,  139,  145,  254, 
202.  3591  concolor,  loa,  106,  121, 
128, 129, 138,  139,  145,  254,  263,359; 
excel8a,88,  359;  firma.  121.  138,  130, 
MS.  »54.  J64,  359;  Fnweri,  58,  1T2, 
118,  254,  255,  359;  grandis.  58,  102, 
105,  121,  255,  261,  359;  lasiocarpa, 
112,  118,  255,  256,  359;  magnifica, 
«02,  105.  121.  25s.  259,  359;  nobilis, 
102,  121,  128,  138,  139,  145,  254 
262,  359;  Veitchii,  112. 118,  255,  257 
359  "     '' 

Abietinex.  14,  71,  ,,5.  ,38,   ,4,,  ,4, 
'44.  "54.  156  ^ 

Acer  campestre,  26;  platanoides,  iw 
rubrum,  25  ''   ' 

Acetic  acid,  21 

Acid,  acetic.  21 ;  hydrochloric,  49;  sul- 
phuric, 49,  igo 
/Kcidium  elatinum,  140 
Aeration,  180 
Aerobes,  180 

Agaricus,  1 78  ;  melleus,    40 
Age  of  trees,  relation  to  j  owth  rincs  2? 
Air  pump,  22  e>      3 

Air,  removal  from  sections,  22 
Akamatsu.  327 
Alcohol.  22.  40,  55,  56 
Algse,  192 
Alkali,  166 

American  A'atiiralht,  15 
American  yew,  213 
Ammonia,  49,  55 
Ammoniacal,  182 
Anaerobes.  180 
Anderson,  A.  P.,  139-141,  148 
Angiosperms.  37,  39,  57 
Anihne  chlonde.  49 
Anthracite,  172 
Anthrax  bacillus,  181 
Araragi,  214 


'5,6.  '97.  *03.  204;  argilliacola,  61; 
anzonicum,6i,  204,  207;  Bidwillii,  29, 
61,    197.   ?04.  205.  358;   brasiliana. 


29;  Cunninghamii,  29.  61.  73,  204. 

,,.c     ,,«.     I.-.:..„.,     .  ,&a,  28, 


Araucaria,  14,  28,29,  50-54,  S7-«i,  65- 
<'7.   70-77.   94.    "8,    120,    122,   151, 


367 


205.  358;  Doeringii,  61  ;  exceia.,  i, 
29.  53.  61,  204,  JOS,  358;  Heerii.6i , 
hugehanum,  61 ;  Kobertianum,  61, 
62,  73;  Schmidianum,6i ;  subtile,  61  • 
virginUnum,  61 ;    wurtembergianum." 

Araucarix,  14 
Araucariinex,  14 

Araucarioxylon,  61,  62,  65,  70,  72,  151, 
156,  204;  Edvardianum,  29,  61,  204, 
208;  Hoppertona;,  204,  208;  obscu 
rum,  204 ;  Prosseri.  204.  207 ;  Virginia- 
num.  204, 206 ;  Woodworthi,  204, 206 
Arbor  vitx,  221 
Arizona,  192 
Ash,  26 

Auriferous  gravels,  164 
Australasia,  4 
Australia,  8 

Bacilli,  182 

Bacillus,  177  ;  anthracis.  181 ;  anthrax, 
181  ;  cholera,  181  ;  hay,  181  ;  sub- 
tills,  181  ;  thermophilus.  181  ;  tuber- 
cle, 181  ;  of  tuberculosis,  181 

Bacteria,  165,  175,  ,77,  ,80,  ,81 

Bald  cypress,  217 

Balm-of-Gilead  fir,  258 

Balsam.  255;  Canada,  21;  mountain, 
256;  she,  255;  xylol,  23 

Balsam  fir,  256,  258,  263;  Canada,  258 

Bastard  cedar,  219 

Big  tree,  225 

Bismarck  brown,  23 

Black  larch.  278 

Black  pine,  328.  334 

Black  spruce.  289 

Blue  spruce,  289 

Bordered  pits,  19,  21,  33,  39,  46,  59. 
77.  '03-105.  113,  114,  129,  x-^^^  ,52, 

,    '55.  '56.  '84.  '88.353  •*•'     ^ 

Bozeman,  166 
Britton.  N.  L„  8 
Brown  coal,  1 72 


368 


ANATOMY  OF  THE  C.YMNOSPERMS 


Brown  rot,  iqo 

Hull  pine,  334,  335,  34J 

Bunya-Bunya,  205 

Calamnpltyi,  154;  latumi,  155 

Caicificaciop,  171,  173 

Calcified,  191 

Calcite,  173,  174 

Calcium  carbonate,  174 

Calcium  oxalate,  109 

California.  16  j 

California  juniper,  166 

California  nutmeg,  21 1 

Campbell,  U.  H.,  25 

Canada,  25,  167 

Canada  baUam,  2 1 

Canada  balsam  fir,  258 

Canadian  Pacific  Railway,  164 

Canoe  cedar,  231 

Carbon,  172,  191,  192 

Carbon  dioxide,  1 77. 

.Carbonization,  171,  173 

Carbureted  hydrogen,  172 

Catalpa,  26,  153,  179;  hardy,  179 

Catalpa  sprciosa,  178,  190 

Cedar,  249;  bastard,  219;  canoe,  221 ; 
ground,  250;  incense,  219;  Oregon, 
2^2;  Port  Oriford,  232 ;  post,  21 9;  red, 
164,  178,  184,  190,  221,  246;  rock, 
249;  shrubby  red,  25 i;  stinking,  211; 
wcritern  white,  231  ;  white,  319,  231, 

Cedar  pine,  323 

Cedar  ties,  170 

Cell  wall,  184,  191 

Cells,  parenchyma,  60,  79,  85,  88,  89, 
93.  100,  105,  115,  116,  128,  131,  135, 
151 ;  ray,  184,  353;  resin,  17,  19,  58, 
89,  111-122,  124-129,  134,  138-142, 

'5>.  353 
Cellulose,  4,    48,   163,   166,  172,   179, 

181,  189,  190,  191 
Celluloxylon  primxvum,  192 
Census,  tenth  United  States,  4,  7,  8, 

162 
Chamxcyparis,  229 
Chamberlain,  C.  J.,  154 
Checkered-barked  juniper,  251 
Chlorophyll,  177 
Cholera  bacillus,  181 
Classification,  193,  105 
Closing  membrane,  59 
Cloves,  oil  of,  23 
Coal,  brown,  172;  soft,  172 
Coleman,  A.  ".,  164 
Colonial  pine,  205 
Colorado  spruce,  289 
Combustion,  spontaneous,  17a 


Common  juniper,  247 

Conflagration,  172 

Coniferje,  14,  35,  39,  40,  43.  49,  58,  60, 
62,  65,  77,  88-90,  102,  105-107,  112, 
129,  '17,  148,  155 

Coniferales,  6,  7,  11,  1  (,  34,  28,  29,  31, 
36.  3^<  44.  57.  58.  <>2.  65,  66,  70,  '71, 
74.  75'  77.  79.  oj.  8'J.  '02,  105,  108, 
109,  III,  118,  143.  148. 151, 154-156, 

•  59.  «95.  *•» 

Coniferous  wood,  184 

Constable,  Howard,  6 

Coonam,  205 

Coorong,  205 

Cordaitacea:,  14,  38 

Cordaitae,  14 

Cordaitales,  14,  28,  29,  31,  36,  57, 
58,  83,  105,  106,  109,  154-i^x),  195, 
198 

Cordaitean,  156 

Cordaites,  60,  67,  71-73.  199,  202;  aca- 
dianum,  60,  67,  71-73,  199,  202;  an- 
nulatum,  73,  199,  201 ;  Brandlingii, 
38,  39.  7,5 ;  Clarkei,  61,  73,  198,  200; 
Tiallii,  199,  202;  hamiltonense,  60, 
7i.  73.  ■99>  200;  illinoisense,  73,  199, 
301;  materiarium,  71,  73,  199,  303; 
materioide,  73,  199,  30i ;  Newberryi, 
60,  61,71,  73,  198,  200;  ohioense,73, 
199,  202;  ouangondianum,  73,  199, 
201;  pennsylvanicum,  198,  199;  re- 
centium,  73,  73,  199,  200 

Cork,  '72,  191 

Coulter.  J.  M.,  154,  155,  160 

Cowdie  pine,  203 

Cretaceous,  <L,3,  174,  192 

Cryplomeria,  14,  51,  76,  83,  117,  144, 
146,    ^97,    2 16;    japonica,    50,    316, 

3' 

C._         .  110,  III,  192 

Crj'        ization,  192 

Cuii    <>tu,  305 

Cupressinex,  14,  19,  57,  112,  117,  119- 
122,  144,  156,  187 

Cupressinoxylon,  13.  230 

Cupressoxylon,  13,  62,  192,  230,  23S ; 
arkansanum,  231,  240;  Calli,  331, 
244;  cheyenneiise,  230,  238;  colum- 
bianum,  231,  241 ;  comanchense,  330, 
239;  Dawsoni,  68,  71,76,  231,  240; 
elongatum,  231,  242;  glasgowi,  331, 
242 ;  macrocarpoides,  230,  23S ; 
McGeei,  231,  243;  pulchellum,  231, 
239;  Wardi,  231,  241 

Cupressus,  10,  i'  14,  33,  51,  76,  82,  8^ 
87-90,  94,  99,  ..J,  105.  107,  115,  145, 
144,  14C,  157,  197,  228,  329,  335; 
arizon'ca,    99,    100,  230,    236,   39; 


INDEX 


Covenltna.  99,  100,  tyo,  »jy,   ,5,,. 

blana.  83,  ijo,  ij6,  359;  macr.Karpa, 
70.  iJo,  jjs.  35<, ,  nootkatennw,  69, 
JHJ.  "9.  JJ3.  359  i  obtuia.  229,  jjj, 
359 i  pi»i/era,  71.,  86.  100,  JJ9  sir, 
J59;  Pygmaa,  8;  thyoidea.  9.1,  iSJ^ 
1 70,  (59  '^     "~' 

Cupnc  acelatc.  55 

Cutin,  191 

fycadac^i,  38,  151,  ,55,  jfe 

Cycadales,  14,  155 

Cycadean,  155 

CycadofiUc...   45,   149,    ,5,,   ,54_,56, 

Cycada,  95.  150,  151 

Cypreas,  236,  237;  bald.  217;  decidu- 
ous,  217;  I^w»on'»,  232;  Monterey, 
J35;  S>"tka,  233;  yellow.  233 

Cysts.  117,  ,24,  128-131,  ,34,  136-146, 

Ciapek.  Fr.,  190 

Dahlonega.  (68 

nammar.  gum.  36 

Dammara,  14,  29.  5,.  54,  57   es,  62,  66. 

67.70.72-7^82.    II9-I22,    ,,,,    ,56, 

«S».   "97.  aoj;  au8tralis,  s4--6.  62. 
65. 66,  203.  358  ^     ■'  • 

Daw-son.  Sir  J.  W..  208.  214 

f,.^2:r\i^'  '^'  33-  35.  37.  39.  44. 

64.  6^,.  88.  104,  129.  ,30.  141,  ,42, 

14".  170 
De  Vries,  M.,  152 
I>e?aYj  163,  175-192 
Deciduous  cypress,  2 1 7 
Desiccation.  181 
Devonian.  11,  171,  17J 
Digger  pine,  342 
Don  River.  214 
Don  valley.  164-769 
Douglas  fir,  31,  32,  52,  ,66.  ,83,   272- 

274  •'•     ' 

Drought,  25,  26 
Dry  rot.  178,  182.  185 
Dudley  P.  H.,  ,70,  ,7,.  .;8,  ,83 
Durability,  ,62-174 

Kichler,  A    E.,  44,   ,09,  ,12,  115,  1,6, 

156 
Elder,  26 
Endophytic,  177 

Kngineering  Building,  MacDonald,  iSi 
Englemann's  spruce,  286 
Kngler,  A.,  7 
Knglish  maple,  26 
Knzymes.  163,  1S8.  ,89 
Eocene.  15, 


369 


Ephedra,  <"•<) 

Kpiphytic.  177 

Kp.theliun..  y.S.  115-1,7,  124-136,  140, 

Ether,  55 

r.usporangiate  femi,  ,49,  ,j. 

Facultative  parasite,  ,78 

Facultative  saprophyte,  it8 

FaguH  sylvatica.  48 

Ferguson,  Margaret  C,  154 

Fernow.  B,  E.,  8.  ,0,  1, 

I'erns.  eusporangiate,  ,49,  |i| 

Fir.  Balmof  (Jilead.  258;  balsam.  256, 
2S».  263:  DouglM.  3,,  32,  52.  166, 
i»3.  272-274;  red,  259,  262;  silver. 
262;  white.   260,  261,  263;  yellow. 

Fires,  forest.  25,  ,72 

Fission  fungi,  ,75 

Flad,  Henry,  6 

Florida,  25 

Food,  i86-)88 

Forests,  petrified,  192 

Fossil  wood,  172 

Fossils.  162-174,  '9' 

Foxtail  pine,  308,  309 

Frost.  25.  26 

Fujimatsu,  280 

Fundamental  tissue.  148,  149.  152 

Fungi.  ,65,  166,  176,  ,77.  ,79,  ,g,-,84, 

189.  ,9,;  fission,  175 
Fungus,  ,77,  185,  187,  ,88 
Fusifc-m  rays.  44,  96,  ,08,  130,  353 

Gases,  172 

Georgia,  168 

Germination,  182 

Ginger  pine,  232 

Gingko,  14,  28,  ;i,  5,  65,  -4,  76, 
82,  9<,  05,  10.,,  119,  (30.  I  ',,  ,96, 
209;  .ioba,  no,  i^  158:  axilla, 
200 

Gingk.iace.T,  14 


Gingkoales,  14.  ;S,  j6,  58.  ..  66, 
70.  74,  83,  106.  109,  i.4-i#ei  ,05, 
209  "^ 

Gingkoinea-,  14 

Gland,  resir,  140 

Glucose.  190 

Gray  pine,  3:1 

(Jround  cedar,  250 

Ground  hemlock,  213 

Gro»;th,  cessation  of,  30;  ecceni  itj 
of.  28;  secondary.   55.  70,  ,04,    •«•- 

^  "af>-.  35.  38 

Growth    rings.    24,    32,    40,    ,,7 
138-140 ;  eccentricity  of,  2S 


I    h 


) 


i  I 


''                1 

370 


ANATOMY  OF  THE  GYMNOSPERMS 


■ 

ife, 

i 

^^Sr 

(ium  damtn»r,  56 

(lymnonpeim*,  13,  33,  36,  38,  57,  58, 

60,  ISO.  153,  154-156 
(lymnosporanglttm  cwvarizlomte,  141 

Hackmatack,  tjA 

lladromal,  190 

Hematoxylin,  Delafiekl'ii,  21 

Hard  pine,  30,  71,  Hi,  85,  87,  89,  100, 

10^,  106,  108,  IJ4,  318 
Hartig,  Cieorg  Ludwtg,  6 
ilartig,  H.,  6,  a6 
lUrtig,  TheiKlur,  6,  l8a 
lUurloria,  177,  186 
Hisartwood,  179 
Hemlock,  178,  a66,  368,  J75;  ground, 

213;  mountain,  269;  western,  270 
Hemlock  ties,  170 
Hcterangium,  1541  Grievii,  73 
Hiba,  215 

Hickory  pine,  309,  337 
HImekomatsu,  316 
Hinoki,  334 
Hoop  pine,  205 
Horse-chestnut,  26 

Idioblasts,  crystallogenous,  109-111 

Inrense  cedar,  219 

Inliltration,  192 

Injuries,  25,  26 

Insects,  21.  36 

Intercellular  spaces,  46,  127 

Intercellular  substance,  46  189 

Interglacial,  11,  165 

Iodine,  49 

Iramomi,  287 

Iron,  sulphide  of,  174 

Jack,  J.  C,  8,  10 

jack  pine,  331 

japan,  4,  8 

Jeffrey,  E.  C,  8,  13,  20,  96,  102,  108, 
122,  g9-lS2'  "54.  "64 

jersey  pme,  338 

Jesup,  M.  K.,  8 

Juniper,  248-253;  California,  166; 
checkered-barked,  251;  common,  247 

Juniperus,  12,  14,  28,  32,  51,  52,82-84, 
87,  88,  94,  99,  100,  105-107,  1 18,  1 19, 
141,  144,  146,  196,  244;  barbadensis, 
8;  cahfomica,  165,  245.  248,  359; 
communis,  12,  140,  J45,  250,  359; 
ci'ii/ugens,  52  (see  j.  sabinoides)  ; 
mono.iperma,  245,  252,  359;  nana, 
12,  88,  245,  251,  359;  occidentalis, 
245-  25".  359 i  rigida,  12,  245,  247, 
359;  sabma,  52,  245,  251,  359;  sabi- 
noides, 245,   249,  359;  scopulorum, 


8 ;  utahensU,  345.  349,  359 ;  virgini' 
ana,  5,  50,  164,  165,  178,  184,  190, 
»45.  H<h  m 

Kansas,  193 
Kaurie,  3oj 
Knob-cone  pint,  jji 
Kuromatsu,  337 

Ijiboratory,  hydiaulk,  183 

Larch,  263,  378  ;  black,  378 ;  mountain, 
380 ;  Tyrolean,  36 

Larix.  10,  14,  44*  47.  5".  7«.  76-78.  83. 
89.90.93-94.96-98.107,114,119-133, 
'1o-'34.  138.  "4^.  "46.  156,  168,  187, 
I  >5,  276;  americana,  34,  40,  41,  43. 
63,  66,  68,  71,  75,  77.  86.  132,  168, 
>77.  '78.  360;  leptolepis,  66,  277. 
280 ;  360 ;  Lyallii.  50.  277.  380.  360 ; 
occidentalis,  77.  132,  143,  276,  377, 

i^^    . 

Lavrson's  cypress.  332 

Leaf  buds,  36 

I^ntinus  lepideus,  170 

I^pidodenaron  selaginoidea,  90 

Libocedrus,  14,  19.  49.  51,  76,  86,  87, 
9^.  95.  "OS.  ii7-"»o,  144,  146,  196, 
319;  decurrens,  50,  319,  358 

Lignification.  48 

Lignified,  163 

Lignilied  wail,  190 

Lignin,  48,  173 

Lignite  Tertiary,  76,  108 

Lignites,  173 

Live  nak,  273 

Ix>blolly  pine,  343 

Ix>dge-pole  pine.  328 

Long-leaved  pine.  ,144 

Lyginodendron.  154 

Mac  Donald  Engineering  Building.  183 

McGill  College.  169 

McGill  University.  183 

Maceration,  5,  69 ;  Schulze't,  49 

Macoun,  John,  214 

Maidenhair  tree,  309 

Maisonneuve,  170 

Maki,  216 

Mangin's  reaction,  49,  190 

Manitoba,  214 

Maple,  English,  26;  Norway,  159,  160 

Marsh  pine,  320 

Maxwell,  E.  J.,  8 

Medullary  rays.  18.  20,  33,  39,  53,  56. 

78-108,  130.135,  141,  143,  151,  152. 

186,  187 
Membrane,  closing  or  pit,  59 
Meristematic,  140 


INDEX 


Mtruliu*  tachrymaiM,  lyS,  iSj 
Mkrotnma,  j} 
Mlnaralization,  17J 
Miocene,  141,  164,  I    I 
Miiwionarieii,  Franciscan,  ji 
Momi,  264 
Montana,  166,  214 
Monterey  cjrprciii,  235 
Monterey  pine,  341 
Montreal,  25,  26,  169,  170 
Moreton  Hay  pine,  205 
Mountain  hemloik,  169 
Mountain  larch,  280 
Mounting  ncctionii,  2j 
Mucilage  canaU,  149,  151 
Mueller,  Harop  K.  von,  i 
Muller,  N.  J.  C,  6 
Muro,  247 

Mycelia,  164-169,  176,  184-      > 
Myxtic  Lake,  166 

Natural  Hiatory  Society  of  Montreal, 

170 
AatUrlichtH  PflanztH/amilitii,  7 
Nedzuko,  122 
Nematophycus,    173;     crassus,     192; 

■•"({ani,  192 
Norulinger,  II.,  6 
Norfolk  Island  pine,  205 
North  America,  4 ;  silva  of,  7,  8 
Norway  maple,  159,  160 
Norway  pine,  325 
Nut  pine,  ^05-307,  310 
Nutmeg,  California,  211 

Oak,  live,  273;  red,  273;  white,  z-ii. 

Oblipite  parasite,  178 

Obli    . •  >  saprophyte,  178 

Oil         .)ves,  23 

Oils,        d,  55 

Old.    .w  pine,  343 

< -regon,  igi 

<^regon  cedar,  232 

ysn-undites  skidegatensis,  171 

OTr.hi.  288  ^^ 

Oxidation,  163,  177 

Otygen,  172,  179,  iSo,  191 

Paleobotany,  151 

Panama  Railway,  170 

Parasites,    140,    141,    177;   facultative, 

178 
Parenchyma  ce!U.,  Oo,  7,,,  85,  88,  89, 

93,    100,    105,    115,    llO,    128,     I  If,     I7C, 

151  ^^ 

Parenchyma  tissue,  f(|2 
Parenchyma  tracheids,  17,  33,  35,  uj, 

117.  «20,  124-136,  140 


37 » 


'V'ri^r* '  '""*■  '^'  "■ "'  ***•  '** 

Parenih)mato.,. .  ii,  js 
Pathological,    <,8 
I'atton  •prii'-- ,  .n,) 
Peat,  17' 
Pectic  aci     4.y 
Pectin,  47 

Pen;    Mow,  I)   P.,  jj.  ,0,.  ,„,  ,4^.  „, 
Penitillium  glaucurn,  i8. 
Peridermium  pini,  140 
Permian,  192 
Petrified  forests,  192 
Phosphureted  hydrogen,  172 
Photography,  23 

Phylogeny,  58,  ,18,  138-153,  ,54.,6, 
Phylum,  148,  155 

Picea.  10,  II.  14.  5,  76,78,82,83.87. 
»9.  90,  9V  94.  '/>-9».  100,  106,  107, 
112,  11(^.121,128,130.133.  134.  ,38- 
146.  156,  167.  187,  195,  281;  afiw, 
'33-  '3-1,  167,  282,  285,  360;  bicolor. 
66,  282,  288,  360;  Hreweriana,  283. 
360;  Engelmanni.  282,  286.  160: 
jesoensis.  283.  287.  36c;  nigra,  131. 
•34.  •67.  169.  232.  289.  360:  polita. 
106,  282,  287,360;  pungens,  134,  ^82, 
J8<;,  360;  rubra,  283,  284,360;  sit. 
chensu-,  134,  281.  290,  360 
Pierce,  j.  C.  148 

Pine,  black.  328.  334;  bull.  334,  335. 
34* ;  cedar,  3.13 ;  colonial,  205 ;  towdie, 
203;  digger,  342;  foxtail,  308,  309; 
ginger,  232  ;  gray,  321 ;  hard,  -o,  71, 
82,  85,  87,  8g,  100,  103,  106,  108.  134, 
318;   hickory,  309,  337;  hoop,  205; 
Jack,  321:    ersey,  338;   knob-cone, 
331 ;  loblo  jr,  343;  long-leaved,  344; 
lodge-pole,  328;  marsh,  320;  Monte- 
rey, 341;  Moreton    Bay,  205;    Nor- 
folk Island,  205 ;  Norway,  325 ;  nut, 
30S-J07.  3'°:  old  field,  343;  pitch, 
3'8.  330;   pond,    320;   prickle<on.-, 
339:     red,     170,    325;    sand,    318; 
scrub.   318.    321.   322.    338;    short 
leaved,   324;    slash,   345;   soft.    71, 
103,   106,    134,   305;    soiedad,   332; 
southern,  162,  344;  spruce,  318,  32^, 
328;  sugar,  311;  swamp,  545;  table 
mountam.    337;    Weymouth.     315; 
white,  162,  312-31$,  317,  323-,  yellow, 
170,324,329,3-3,335,345 
Pinoidea:,  14 
Pinon,  305-307,  310 
Pmoxylon,    13.   304;    dacotense,   304, 

346 
Pinus,  10-14.  '9.  44.  47.  Si,  62,  66,  68, 
71.   75-83.  85.  88-89,   99.   103-108, 


i: 


372 


ANATOMY  OF  THE  GVMNOSPERMS 


112,  116-121,  129,  133-136, 138-146, 
156,  158,  160,  195,  291,  292,  305; 
albicaulis,  96,  294,  316,  361 ;  aristata, 
93,  108,  293,  309, 360  ;  arizonica,  108, 
304,  329,  361  ;  Balfouriana,  86,  293, 
308,  360;  Banksiana,  296,  299,  321, 
361 ;  cembroides,  293,  306,  360;  chi- 
huahuana,  300,  333,  361;  clausa,  71, 
77.  89.  93.  98.  99.  «03,  104,  296,  297, 
318,  361 ;  Columbiana,  304,  348 ;  con- 
torta,  13,  299,  322,  361  ;  Coulteri,  81, 
108,  301,  330,  361  ;  cubensis,  26,  63, 
68-71,  79,  81,  84,  89,  92,  93,  100, 
108,  134,  13s,  296-299,301-303,  344, 
361  ;  densiilora,  93,  295,  321,  361  ; 
echinata,  11,  26,  297,  324,  361; 
edulis,  108,  293,  310,  360;  flexilis, 
294.  3^3<  361;  glabra,  11,  93,  100, 
108,  298,  300,  302,  304,  323,  361; 
inops,  81,  89,  104,  108,  302,  304, 
338,  361 ;  insignis,  69,  81,  108,  303, 
341,  361  ;  Jeffreyi,  13,  80,  92,  108, 
3°'.  334.  361 ;  koraiensis,  84, 92,  104 ; 
Lambertiana,  71,  77,  103,  135,  136, 
294,  311,  360;  monophylla,  86,  93, 
292,  307,  360;  monticola,  93,  294, 
312,  ;6o;  muricata,  300,  301,  339, 
361  ;  Murrayana,  12,  81,  92,  99,  100, 

103,  108,  296,  301,  328,  361 ;  palus- 
tris,  26,  ',1,  51,  71,  77,  80,  89,  92,  93, 
96,  97,  1  I,  105,  106,  162,  170,  277, 
298,  302,  303,  344,  361  ;  Parryana, 
106,  292,  305,  360;  parviflora,  294, 
316,  361  ;  ponderosa,  13,  96,  97,  108, 
302,  334,  361;  pungens-,  68,  81,  89, 

104,  108,  134,  135,  299, 302,  337, 361 ; 
reflexa,  78,  79,  84,  95,  135,  293,  314, 
361 ;  resinosa,  31,  84,  92,  105,  170, 
188,  295,  325,  361  ;  rigida,  103,  104, 
296,  298,  299,  300,  318,  361  ;  Sabin- 
iana,7l,  77, 108,  303,  342,  361  ;  scopu- 
lorum,  301,  337,  361 ;  serotina,  85, 99, 
298,  299,  320,  361 ;  strobus,  63,  64, 
68,  69,  162,  299,  315,  361 ;  sylvestris, 
69;  tajda,  II,  34,  40,  41,  43,  6g,  71, 
77,  80,  84,  89,  91-93.  105-108,  134, 
296-298,  301-303,  343,  361 ;  Thun- 
bergii,  92,  105,  295,  327,  361  ;  Tor- 
reyana,  31,  89,  303,  332,  361  ;  tropi- 
calis,  295,  326,  361 ;  tuoerculata,  303, 
331,  361 J  7'irjrint(ina.  See  Pinus 
inops. 

Pit  membrane,  59 

Pitch  pine,  318,  330 

Pits,    187;  bordered,    19,  21,   113,   114, 

129,  133,  152,  155,  156;  multiseriate, 

67 
Pitted  tracheids,  17,  ^i,  34,  45-53 


Pityoxylon,  13,  108,  192,  304,  346; 
Aldersoni,  304,  346;  amethystinum, 
304,  347;  chasense,  20,  305,  349; 
Peali,  305,  349 ;  scituatense,  305, 350 ; 
statenense,  305,  349 

Pleistocene,  5,  21,  164,  167,  168 

Podocarpacex,  14,  83 

Podocarpus,  14,  51,  74,  76,  112,  115- 
119,  122,  144,  146,  197,  216;  macro- 
phylla,  216,  358 

Polypori,  178,  185 

Polyporus,  catalpx,  179;  juniperinus, 
185,  190;  Schweinitzii,  191;  sulphu- 
reus,  191  ;  vaporarius,  191  ;  versi- 
color, 163,  179,  190 

Pond  pine,  320 

Poroxylon,  155,  156,  160 

Port  Orford  cedar,  232 

Post  cedar,  219 

Potassium  hydrate,  47,  55,  56 

Prantl,  K.,  7,  138,  149 

Presers-ation,  162-174 

Prickle-cone  pine,  339 

Primary  wall,  46,  49,  59 

Process  plates,  23 

Prosenchymatous,  33 

Protodammara,  203 

Protoplasm,  181 

Protoxylem,  38,  40,  59,  155 

Pseudotsuga,  9-14,  27-51,  76,  77,  82, 
88,  90,  93-98,  107,  1 14-122,  130-134, 
138,  142-146,  156,  195,  271  ;  Doug- 
lasii,  12,  26,  27,  31,  41,  43,  96,  131, 
166,  271,  272,  360;  macrocarpa,  12, 
41,  43,  52,  106,  131,  166,  271,  275, 
360;  miocena,  43,  191,  272,  276 

Pteridophytes,  35 

Pyritization,  171,  174 

Queen  Charlotte  Islands,  i ,  4 
(juercus  alba,  273;  rubra,  273;  virens, 
273 

Radial  sections,  18,  79;  wall,  60,  136 
Ray  cells,  184;  fusiform,  44,  96,  108, 

>30.  353:  medullary.  18,  20,  33,  3<). 

S3.  56.   78-108,  130,    135,  141,  143. 

151,  152,  186,  187;  tracheids.  33,35, 

85.  88-93,  'OS,  105-108,  115,  ^53 
Red  cedar,  164,  178,  184,  190,  221,  241') 
Red  fir,  259,   262 
Red  oak,  273 
Red  pine,  170,  325 
Red  spruce,  284 
Redpath  Museum,  l6<; 
Redwood,  224 
Reservoirs,  secretory,  58,  1 23,  1 28,  1 30, 

136-  MS 


INDEX 


373 


Resin  canals.    Ste  Resin  passages 
Kesin  cells,  17,  19,  58,89,  111-122,  124- 

129.  134.  138-142.  IS".  353 
Resm  cysts,   17,  19.  58,  1 21-124,  "3«- 

146,  150,  152 
Resin  flux,  140 
Resin  gland,  140 
Resin  passages,  17,  18,  19,  20,  44,  58, 

78,  79,  89,  98,  108,  111-155,  '87,  353 
Resinous  tracheids,  34,  53-58,  120,  123 
Rhizopus  nigricans,  183 
Rhus  typhina,  26 
Rock  cedar,  249 
Rocky  Mountains,  214 
Rot,  brown,  190;  dry,  178,  182,   185; 

soft,  190;  white,  190 
Ruthenium,  red,  47,  49 

Salicacex,  153 

Salisburia,  209 

Sambucus  racemosa,  26 

Sand  pine,  318 

Sanio's  bands,  53,  55 

Saprophyte,     177;     facultative,     178; 
obligate,  178 

Sargent,  C.  S.,  4,  7,  8,  13,  162 

Savin,  211,  246 

Sawara,  233 

Scalariform,  38 

Scarborough  period,  167 

Schizogenously,  46,  116 

Schizomycetes,  175 

Schrenk,  H.  von,  163,  178,  179,  190 

Schulze's  maceration,  49 

Scott,  D.  H.,  155,  160 

Scrub  pine,  318,  321,  322,  338 

Secondary  growth,  70,  104,  189 

Secondary  wood,  34,  155 

Secretory  reservoirs,  58,  123,  128,  130, 
136,  145 

Sections,  mounting,  22 ;  preparation  of, 
21;  radial,  18;  removal  of  air  from, 
22;  tangential,  iS,  no,  in;  trans- 
verse, 17 
Sequoia,  10,  13,  14,  19,  25,  51,  52,  62, 
68,  75-77.  82-87,  94.  99.  100,  107, 
112-123,  127-129,  141,  143-152,  157, 
196,  223;  Burgessii,  20,  96,  108,  126, 
142,  151,  224,  226;  gigantea,  52,  65- 
67,  84,  86,  139-144,  152,  157,  223, 
225.  358;  I^ngsdorfii,  142,  144,  324. 
226;  magnifica,  233,  226;  I'enhal- 
lowii,  96,  102,  108,  126,  140-144,  148, 
164,  224,  228;  sempervirens,  52,  86, 
94,  113,  114,  117,  121-127,  I4«-I44, 

148,157,195,233,224,358 
Mie  balsam,  255 

Shirabe,  257 


Short-leaved  pine,  324 
Shrubby  red  cedar,  251 
Sierra  Nevada  Mountains,  164 
.Sigillaria,  75 
Silica,  192 

^ili'^ffi""''?;5. '67.  171.  173.  174 
Sihcified,  166,  172,  191 

Silurian,  171 

Silva  of  North  America,  7,  8 

Silver  fir,  262 

Sitka  cypress,  233 

Sitka  spruce,  290 

Slash  pine,  345 

Sodium  carbonate,  21 

Soft  coal,  172 

Soft  rot,  190 

Soledad  pine,  332 

Southern  pine,  344 

Spiral  tracheids,  17,  21,  33-45,  152,  353 

Spirillum  cholera-asiatica-,  181 

Spontaneous  combustion,  172 

Spores,  176,  181,  182,  184 

Spring  tracheid.s,  52,  86,  87 

Spring  wood,  17,  31,  30,  33,  49,  50,  58, 
00,69,  «04.  no,  117,  127,  128,  131- 
'34.  139-M2,  166,  184,  273 

Spruce,   black,  289;   blue,  2S9;    Colo- 
rado,  289;  Engelmann's,  286;    I'at 
ton,  369;   pine,  318,   333,   32S;    red, 
284 ;  Sitka,  2(>o ;  tideland,  290 ;  weep- 
ing, 283 ;  white,  285,  286 
Staining,  22 
Starch,  179 
Stigmaria,  95 
Stinking  cedar,  211 
Stratification,  47 
Striation,  47,  69,  191 
Sugar,  179 
Sugar  pine,  311 
Sugi,  316 

Sulphide  of  iron,  174 
Sulphuric  acid,  49,  190 
Sumac,  26 

Summer  tracheids,  43,  52,  86 
Summer  wood,  17,  21,  31,  32,  39,  49, 
50,  58,  68,  69,  92,  104,  no,  117,  118, 
121,  128,  131,  132,  134,  138-145,  166, 
^  '84.  273.  353 
Swamp  pme,  345 
Systematic,  193,  195 

Table  mountain  pine,  337 
Tamarack,  377,  378,  280 
Tangential  sections,  18,  70,  no,  ni 
Tangential  walls,  65,  66,  75,  129,  136 
Taxacea-,  14,  40,  66,  74,  77,  105,  106, 

n2 
Taxodiinex,  14,  19,  156 


374 


ANATOMY  OF  THE  GYMNOSPERMS 


Taxodium,  lo,  14,  19,  51,  76,82,84,87, 
1 12-122,  144,  196,  217;  distichum, 
31,  81, 87,  217  ;  laramianum,  217,  218 

Taxus,  9,  14,  28,  ,)2, 34,  37, 40, 4 1, 44,  47, 
69,76,99,  112,  119,  144,  148,  151,  184. 
196,  212;  brevifolia,  42,94,  213,  214, 
358;  canadensis,  42,  50,  51,  212,  213, 
358  ;  cuspidata,  42,  99,  213,  214, 358 ; 
floridana,  42,  74,  213,  358 

Temperature,  181,  182 ;  maximum, 
182;  minimum,  181 ;  optimum,  181 

Tenth  census  of  the  United  States,  4, 
7.8 

Tertiary,  76,  164 ;  lignite,  76,  108 

Tertiary  wall,  36,  40,  47,  190 

Thiselton-Dyer,  Sir  W.  T.,  8 

Thujopsis,  14,  51,  76,  82,  117-119,  144, 
146,  197,  215;  dolabrata,  215,  358 

Thuya,  10,  14,  32,  51,  76,  82,  89,  99, 
107,  117,  119,  122,  144,  146,157,  197, 
220;  gigantea,  82,  88,  99,  220,  221, 
358;  -iponica,  88,  220,  222,  358; 
occidentalis,  220,  221,  358 

Thyloses,  79,  126,   129,  131-137,  143, 

353 

Tideland  spruce,  290 

Ties,  cedar,  170;  hemlock,  170 

Tissue,  fundamental,  148,  149,  152; 
wood,  172,  186 

Tissues,  lignified,  163,  189 

T6hi,  287 

Toronto,  164,  167,  214 

Torreya,  9,  14,  32,  34,  37,  40-47,  ct, 
S*>  09.  75'  99.  H2.  119.  '44.  151.  184, 
196,  210;  califomica,  41,  43,  74,  210, 
211,  358;  nucifera,  41,  66,  74,  99, 
210,  212,  358;   taxifolia,  41,  49,  66, 

69.  7«.  74>  77.  2«o.  2".  358 

Tracheae,  39 

Tracheids,  17,  21,  30,  33-58,  140,  141, 
152,  169,  184,  186,  188;  parenchyma, 
«7.  33.  35.  «i5-"7.  120,  124-136, 
140;  pitted,  17,  33,  34,  45-53;  ray, 
33.  35.  85.  88-93,  '02,  105-108,  115; 
resin,  34,  53-58,  120,  122;  spiral,  17, 
21.  33-45.  «52.  353!  spring,  52,  86, 
87;  summer,  43,  52,  86;  wood,  30, 
34, 88, 105, 1 10, 1 15, 127, 128, 132, 136 

Trametes  pini,  190 

Transition,  31  ;  zone,  19,  152 

Trinsverse  sections,  17 

Ti   umatic,  141,  148 

Ti  es,  age  of,  25 

Tsuga,  10,  14,  51,  76,  83,  88,  90,  93, 
107,  114,  116,  118-123,128,  129,  139- 
148,  156,  197,  265,  267;  canadensis, 
63.  71.  77.  «70.  >78,  265,  266,  359; 
caroliniana,  127,  129,  138,  145,  266, 


359;  Mcrtensiana,  128,  129,  132,  i^S, 
142,  145,  195,  265,  270,  360;  Pat 
toniana,  266,  269,  359 ;  Sieboldii,  50, 
266,  267,  3S9 

Tubercle  bacillus,  181 

Tubeuf,  K.  F.  von,  6,  140,  190 

Tumor,  148 

Tyrolean  lar:!),  26 

Vallisneria  spiralis,  165 
Vascular  plants,  192 

Walchia,  156 

Wall,  cell,  184 ;  lignified.  190;  primary, 
46,  49.  59.  189,  190;  radial,  60,  136; 
secondary,  36,  40,  47,  49, 60,  69,  169; 
tertiary,  36,  ao,  47,  190;  tangential, 
65,  66,  75,  I.J,  136 

Wanning,  E.,  181 

Weeping  spruce,  283 

Weiss,  G.  A.,  48 

Western  hemlock,  270 

Western  white  cedar,  22 1 

Western  yew,  214 

Weymouth  pine,  315 

White  cedar,  219,  221,  232 

White  fir,  260,  261,  263 

White  oak,  273 

White  pine,  162,  312-315,  317,  323 

White  rot,  190 

White  spruce,  285,  286 

Wittstein,  G.  C,  55 

Wood,  coniferous,  184;  durability  of, 
162-174  i  fossil,  172  ;  preservation  of, 
162, 174;  secondary,  34,  155;  spring, 
17,  21,  30,  32,  49,  50,  58,  66,  6q,  104, 
no,  117,  127,128,  131,  134,  139-142, 
166, 184,  273 ;  summer,  17,  21,  31,  32, 
39.  49.  SO.  58. 68,  69,  92, 104,  no,  117, 
1 18,  121,  128,  131,  132,  134,  138-145, 
166,  184,  273,  353 

Wood  parenchyma,  17,  53,  55,  58,  109 
112,  122 

Wood  parenchyma  tracheids,  35 

Wood  tissue,  172,  186 

Wood  tracheids,  30,  34,  88,  105,  1 10, 
115,  127,  128,  132,  136 

Xylem,  149 
Xylol  balsam,  23 

Yellow  cypress,  233 

Yellow  fir,  272 

Yellow  pine,   170,  324,  329,  333,  335, 

345 
Yew,  214;  American,  21?:  western,  214 

Zea,  35 


PLATES 


PLAT.  ..    PS.UOOTSUO.  Douo^sn      ^Vansverse  section  showing  the  Structure 
of  the  fine-grained  wood,    x  41.2 


Plate  2.   Torreya  taxifolia.    Transverse  s«-tmn   =k      • 

of  growth  nngs  in  an  ^rl^eTl^nr  x^f  '^"^'^^""'^'^ 


I?' 


Platr  3.  foRDAiTES  Hrandlingii.  Radial  section  of  the  transition  zone  next 
the  pith,  showing  the  protoxylem  to  be  wholly  composed  of  spiral  tracheids. 
X  IS3-4 


Plate  4.  Cordaites  Brandlingii.  Radial  section  of '  transition  zone  imme- 
diately external  to  the  preceding,  and  showing  the  spirals  of  the  tracheids 
passing  into  scalariform  structure,    x  153.4 


Plate  s.   Cordaites  BRAvniisim     boj:..i 


forced.  n.u..Ueria.e   boSd  pits      x  S"  '"■"'""  '"'"  ™''""=^'" 


I'l.ATE  7.    CoRDAlTKS  ACADIANi'M.    Radial  section  showirijj;  the  completed  bor- 
dered pits  with  a  primitive  arrangement,     x  180 


Plates,   (ordaitf.s  Nf.wberryi.    Radial  section  showing  the  peculiar  group- 
ing of  the  bordered  pits.     X  180 


} 


Plate  9.   rrrRF.ssrs  n-.m.tkatf.nsis.    Radial  section  showing  the  longituclinal 
distribution  of  fungus  mycelia  in  the  tracheids  of  the  wood,     x  .50 


l.n 


Platk  10.   Cui-iKssus  NooTKATENSi:     Radial  Section  .iu.wing  the  transverse 
.s.r,bu.,on  of  fungus  .yce.ia  in  the  tracheids  of  the  wood,  and  their  relli 
to  the  trachetd  walls,     x  150 


•i 


il 


PIJ4TF.  II.  PsEUDOTSUGA  MiocENA.  Radial  section  showing  the  effects  of  flecav 
in  lireaking  up  the  nuljgtance  of  the  cell  wall  along  the  lines  of  »t  iution. 
X  137-8 


Plate  12.  Cordaites  materiakium.  Transverse  section  showing  the  absence 
of  growth  rings,  the  character  of  the  tracheids,  and  the  distribution  of  resinous 
tracheids  near  the  medullary  rays.    X  40.9 


Plate  13.  Cordaitf.b  mateharium.   Tangential  section  nhowlng  the  character 
of  the  ordinary  medullary  rays  which  are  sometimes  two-seriate,    x  40.9 


Plate  14.  Dammaea  austhaiis.  TransversesiectionHhowing  the  dearly  defined 
growth  ring  and  its  summer  wood,  and  the  distribution  of  resin  cells  near  the 
medullary  rays,    x  46.8 


m 


Platk  ij.    Dam^'ara  At'sTRALls.    Tangential  section  xhowing  the  character  of 
the  nirilullarv    ay>  ^nd  the  occurreno.  and  location  of  plate:*  of  resin,    x  Si 


^ 


PlJ»TE  i6.  Araucaria  glauca.  Transverse  section  showing  the  general  chai- 
acter  of  the  structure,  the  absence  of  growth  rings,  and  the  distribution  of 
resinous  tracheids.     X  46.S 


i 


^itimiiiiMi 


i'lATK  17.   A.AI  CAEIA  01.AI  cA.    Tangential  section  showing  the  character  of 
the  medullary  ray*,     x  46.8 


PIATE  ,8.  r.lNOKo  RiroBA.  Transverse  .Pcnon  .howing  the  dcvelopn.^.U  .,1  a 
-strong  growth  rmg.  and  the  occurrence  of  crystals  as  indicated  by  dark  spots 
in  line  with  the  tracheids.     x  46.8 


\ 


Pl.ATK  i<).    CilNGKO  BILOBA.    Tangential  section  showing  the  character  of  the 
very  low  medullary  rays.     X  52 


if' 


W.'l 


till  ill   liilWWMA 


Pl.ATK  .'O.   ToRRFVA  TAXIFOMA.    Transverse  section  showing  the  Very  thin  and 
open  summer  wood,    x  46.8 


Pl-ATK  21.    ToRREYA  TAXIKOLIA.    Tangential  section  showing  the  character  of 
the  medullary  rays,     x  52 


Plate  21.    Taxus  tusnUAiA.    Transverse  section   showing   the   rather  dense 
structure  of  the  thin  summer  wood,     x  46.8 


If 


wk 


Platk  2J.  Taxus  crspiDATA.    Tangential  section  showing  the  character  of  the 
very  narrow  and  rather  high  medullary  rays,   x  52 


Plj^TE  24.  Thl'Jopsis  dolabrata.  Transverse  section  showing  the  narrow 
growth  rings,  the  thin  summer  wood,  and  the  distribution  of  resi:i  cells  in 
the  spring  wood,    x  46.8 


Plate  25.   Thujopsis  noiABRATA.    T 
of  the  low  rays  in  the 


'  i 


angential  section  showing  the  character 
pring  wood,    x  52 


Plate  -6.   fKYrroMERiA  japoNica.    Transverse  section  showing  the  very  dense 
summer  wood  and  the  distribution  of  resin  cells,     x  46.8 


II 


lij 


f»"' 


Plate  27.   Cryptomf.ria  japonica.    Tangential  section  showing  the  cliaracter 
of  the  iow  rays  in  the  spring  wood,     x  52 


Pl^TE  28.    PoDOCAKi'ts  MACKufllYl-LA.    Transverse  Section  shutting  the  general 
structure  and  the  distribution  of  the  numerous  resin  cell-s.     x  46.8 


Pl.\te  29.  PonocARPUs  MACROPHYLLA.  Tangential  section  showing  the  struc- 
ture and  very  resinous  character  of  the  medullary  rays,  in  the  region  hetween 
the  spring  and  summer  »c;ds.     x  46.8 


Plate  jo.  Taxodium  distichum.  Transverse  section  showing  a  double  zone  of 
summer  wood  a:id  the  distribution  of  resin  cells  in  tangential  rows,     x  4C.8 


Pi.ATK  31.    Taxodu'M   nisTiriii'M.    Tangential  section  showing  tlie  character 
of  the  medullary  ray.s      x  46.8 


Platk  32.    LlBOCEDRUS   DECURRENS.    Transverse  section  showing  the  dense 
summer  wood  and  the  distribution  of  the  resin  cells,     x  46.8 


Platf  V3.    LiBOCEDRirs  DKCURRENS.    Tangential  section  showing  the  character 
of  the  rather  broad  medullary  rays  and  the  occurrence  of  re-sin.    x  64 


iiiiiiiilijlliiipwiiiililiiiiiii 


Plate  34.    Thuya   occidentalis.    Transverse   section    showing  the  narrow 
cX     xTs  "^  '''"  """""  *°°''  '""'  '""^  •1-'"'^'"'-  of  the  r^:: 


fi 


Plate  35.  TiirvA  ornnF.NTAl.ls.  Tangential  section  showing  the  very  narrow 
medullary  rays  with  narrowly  oblong  cells,  taken  from  the  spring  wood. 
X  64 


Platk  ^6.  Seqi'OIA  sempervirens.  Transverse  section  showing  the  very  large 
tracheids  of  the  spring  wood  with  thin  walls,  the  rather  dense  summer  wood 
with  a  somewhat  abrupt  transition  from  the  spring  wood,  the  scaUering  dis- 
tribution of  the  resin  cells,  and  the  occurrence  of  resin  sacs  in  the  initial  layer 
of  the  spring  wood.     X  46.8 


1 


Plate  37.  Skqi-ou  skmpervirf.ns.  Tangential  nection  from  the  spring  wood 
showing  the  very  broad  medullary  ray.s,  the  celU  of  which  are  equal  and 
uniform,     x  64 


Plate  38.    CrpREssirs  Goveniana.    Transverse  section  showing  the  very  thir 
summer  wood  and  the  distribution  of  the  resin  cells,    x  46.S 


Platk  39.   CuPKESSt's  GovKNiANA.    Tangential  section  showing  the  very  liroad 
itnd  low  medullary  rays,    x  ji 


-» 


Plate  40.   Ji'NiPF.Rt's  californica.    Transverse  section   showing   the  char- 
acter of  the  growth  rings  and  the  distribution  of  the  resin  cells,     x  46.8 


Plate 


spring 


Pl-ATF  )3,  .MslFS  NOBu.is.  Transverse  section  showiilg  the  otcurreiKe  , if  resin 
canals  and  the  distribution  of  scattering  resin  ceVi  on  the  outer  face  of  the 
summer  wood,    x  39.2 


I'LATK  4J.    AbiKS  Nubii.is.    Tangential  xntinn  xhowing  the  character  nf  the 
medullary  rayi*.    x  46.8 


Flatk  44.  TsuGA  Pattoniana.  Transverse  section  showing  the  character  of 
the  summer  wood  and  the  distribution  uf  the  resin  cells  on  the  outer  face 
of  the  growth  ring,     x  46.8 


I'LATK  4S.   TsioA   Pattonian*.    Tangenlial  se<ti..n  through  the  spring  wo.ul 
showing  the  character  of  the  nieduliary  ray».     x  4bJi 


•  t 


•••<iift«;«« 


PiATK  46.  PsEUDOTSfOA  noroLASTl.  Transverse  section  ,hov^l..K  the  broaU 
and  dense  summer  wood  in  a  coarse-grained  form,  and  the  distribution  of 
the  resin  canals,     x  46.8 


ri.ATE  47-  PsEl'DoTsrcA  Doroi.ASll.  Tangential  section  showing  the  low  and 
broad  ordinary  rays,  together  with  the  often  very  unequal  and  narrow  fusi- 
form rays,     x  46.S 


Pi.ATF,  4S.   Larix  AMERICANA.    Transverse  Section  showing  the  dense  and  broad 
summer  wood  and  tile  distribution  of  resin  canals,    x  46.8 


Plate  49.   Larix  Americana.    Tangential  section  from  the  spring  wood  show- 
ing the  narrow  ordinary  rays  and  the  rather  broad  fusiform  rays,    x  46.8 


Plate  50.    Picea  nigra.    Transverse   section  showing  the  character  of  the 
general  structure  and  the  distribution  of  the  resin  canals,     x  46.8 


Plate  si-    Picf.a  nigra.    Tangential  section  through  the  spring  wood  showing 
the  structure  of  the  two  forms  of  medullary  r  ys.     x  46.8 


Plate  52.  Pinis  monticola.  (Type  of  soft  pines.  Sec.  I.)  Transverse  section 
showing  the  large  and  thin-walled  tracheids  of  the  spring  wood,  the  very  thm 
and  open  summer  wood,  the  large  resin  canals  with  the  associated  paren- 
chyma broken  out.     x  46.8 


PlATK  53-    PiNUS  MONTICOLA.    Tangential  section  showing  the  structure 
two  forms  of  medullary  rays.    X  46.8 


)f  the 


Plate  54.  Pini's  glabra.  (Type  of  hard  pines,  Sec.  II.)  Transverse  sec- 
tion showing  the  very  broad  and  very  dense  summer  wood,  and  the  structure 
of  a  resin  canal  with  very  large  epithelial  cells,    x  46.8 


Plate  s.?.  Pinus  glabra.  Tangential  section  through  the  spring  wood  showing 
the  ordinary  rays  with  terminal  tracheids  and  witu  the  thin-walled  paren- 
chyma all  broken  jut;  the  interspersal  of  the  tracheids  and  their  general 
predominance;  the  structure  of  the  low  and  rather  broad  fusiform  ray,  the 
thin-walled  parenchyma  cells  of  which  have  been  broken  out,  leaving  only  a 
portion  of  the  resm  canal  in  the  central  tract  together  with  the  terminal 
tracheids.    x  46.8 


a 


^ 


